Category: 1. Immunizations

Immunizations keep children healthy. Vaccines are safe, effective, and they save lives.

However, parents may still have questions about why vaccines are needed. Some may be concerned about vaccine safety because they have been misinformed. That’s why it’s important to turn to a reliable and trusted source, including your child’s doctor, for information. Read on for answers to some common questions parents have about vaccines.

Why are vaccines still needed if the diseases are not as common anymore?

Many diseases are not as common as they once were because of vaccines. However, the bacteria and viruses that cause them still exist and can still make children very sick.

For example, before the Hib vaccine was developed in the 1980s, there were about 20,000 cases of Hib disease in the United States a year. Today there are fewer than 100 cases a year. However, the bacteria that causes Hib disease still exists. That is why children still need the vaccine to be protected.

In the United States vaccines protect children from many diseases. However, in many parts of the world vaccine-preventable diseases are still common. Because diseases may be brought into the United States by Americans who travel abroad or from people visiting areas with current disease outbreaks, it’s important that your child is vaccinated.

Chickenpox is not a fatal disease, so why is the vaccine needed?

Chickenpox is usually mild. However, there can be serious complications. In fact, before the vaccine was licensed in 1995, there were about 4 million cases, 11,000 hospitalizations, and 100 deaths each year from chickenpox. Chickenpox is also very contagious. Most children feel miserable and miss a week or more of school when infected. It is because of the vaccine that the number of cases of chickenpox and its complications, including deaths, have gone down so dramatically.

Does my baby need immunizations if I am breastfeeding?

Yes. While breastfeeding gives some protection against many diseases (and is the best nutrition for your baby), it is not a substitute for vaccines. In fact, breastfeeding and vaccines work well together. Studies show that breastfed babies respond better to vaccines and get better protection from them than babies who are not breastfed. And breastfeeding during or right after immunizations may help calm babies upset by the shots.

Do vaccines even work? It seems like most of the people who get these diseases have been vaccinated.

Yes. Vaccines work very well. Millions of children have been protected against serious illnesses because they were immunized. Most childhood vaccines are 90% to 99% effective in preventing disease. Children who aren’t vaccinated are much more likely to get a disease if they are exposed to it. And if a vaccinated child does get the disease, the symptoms are usually milder with fewer complications than in a child who hasn’t been vaccinated.

When should my child get immunized?

Children should get most of their shots during their first 2 years after birth. This is because many of these diseases are the most severe in the very young. Most newborns receive their first shot (hepatitis B) at birth before leaving the hospital, and more are given at well-child checkups in the first 6 months after birth. Other shots are given before children go to school. Older children and teens need vaccines to continue to protect them throughout adolescence and early adulthood. (Parents and caregivers also need vaccines so that they can prevent bringing infections home to their children and to keep themselves healthy so that they can care for their children!)

Children who are not immunized or who are behind​ on their shots are at risk of getting many of these diseases. They can also spread these diseases to others who have not yet been immunized. Ask your child’s doctor if your child is up to date. Keep track of the vaccines each child receives and bring this information to each doctor visit.

What side effects will my child have after getting a vaccine? Are they serious?

There may be mild side effects, such as swelling, redness, and tenderness where the shot was given, but they do not last long. Your child may also have a slight fever and be fussy for a short time afterward. It is rare for side effects to be serious. However, call your child’s doctor right away if you have any concerns after vaccines are given.

Should some children not be immunized?

Children with certain health problems may need to avoid some vaccines or get them later. In most cases, children with cancer, those taking oral or injected steroids for lung or kidney conditions, or those who have problems with their immune systems should not get vaccines that are made with live viruses. To protect these children it is very important for others to be vaccinated. On the other hand, a child with a minor illness such as low-grade fever (<100.4°F), an ear infection, cough, a runny nose, or mild diarrhea can safely be immunized.

Does the MMR vaccine cause autism?

No! The MMR vaccine does not cause autism spectrum disorder (ASD). Many research studies have been done to address this issue. There may be confusion because children with ASD are often diagnosed between 18 and 30 months of age—around the same time the MMR vaccine is given. This has led some people to assume that the vaccine is the cause. Increasing evidence shows that even though the symptoms of ASD may not be visible until the second year after birth or later, ASD starts before a baby is born.

Do vaccines cause SIDS?

No! Babies get many of their first vaccines between 2 and 4 months of age. This is also the peak age for sudden infant death syndrome (SIDS​), which is why some people feel they might be related. However, careful scientific studies have confirmed that vaccinations not only do not cause SIDS but may help prevent it.

How do we know vaccines are safe?

The safety and effectiveness of vaccines are under constant study. Because vaccines are designed to be given routinely during well-child visits, they must be safe. Safety testing begins as soon as a new vaccine is considered, continues until it is approved by the US Food and Drug Administration (FDA), and is monitored indefinitely after licensure. The AAP works closely with the Centers for Disease Control and Prevention (CDC) to make recommendations for vaccine use.

What is thimerosal and does it cause neurologic problems?

In the 1930s a preservative called thimerosal was added to vaccines to prevent contamination of vaccines. Thimerosal contains very small amounts of mercury, but it is in a different form than the potentially harmful mercury we are all exposed to in the environment. Even after many studies, the type of mercury in thimerosal has never been shown to cause health problems other than rare allergic reactions in some people. Thimerosal does not cause neurologic problems. Since 2001 all vaccines for infants either are thimerosal-free or contain only trace amounts of the preservative. Many are available in single-dose, preservative-free forms.

Is it safe to give more than one vaccine at a time?

Yes! Your child’s immune system is capable of handling multiple vaccines at a time. Many years of experience and careful research have shown that routine childhood vaccines can be given together safely and effectively. Side effects are not increased when vaccines are given together.

​​​​​​Did you know the overwhelming majority of parents vaccinate their children?

In an effort to transform statistics into real conversations about how children and families benefit from immunizations, the American Academy of Pediatrics (AAP) asked parents to send in personal stories and testimonials about why they vaccinate their children. 

Here’s What You Told Us:

I value caring for my baby.  

• “There are SO MANY things I cannot protect my child from, so I will take every safe and healthy way to protect her that I can find. Vaccinating her from potentially deadly diseases is a gift—one that she needs now that diseases we thought we had conquered are starting to come back.”   —Bonnie Stetz, Mom
• “As parents, we of course want to protect our children from serious danger. Even more so though, we want to say we did our best to ‘prevent the preventable risk’. I couldn’t imagine my child coming down with a disease that we had the opportunity to provide some sort of barrier against, but didn’t.”   —Kara Hepp, Mom
• ​”I vaccinate to prevent my four children from contracting horrible diseases—the exact reason vaccines were developed! Thankfully, we live in a time where this is possible. All children deserve the gift of wellness.”   —Teresa Motz, Mom
• “I vaccinate, because I want to keep my children safe. It’s the same reason that they wear helmets and seatbelts.”   —Kelly Hargraves, Mom
• “I vaccinate my kids, because I believe in providing them with the best healthcare possible. Vaccinations play into that because they protect children from harmful, sometimes deadly diseases. Failing to vaccinate intentionally puts my kids (and others’ kids) at risk. We’re fortunate to live in a country that makes such vaccinations available. ”   —Marina Mayer, Mom
• “I vaccinate, because I want my daughter to be as healthy as possible. Vaccination is one incredibly important way to guarantee that!”   —Jessica Hodgson, Mom

I value caring for my community.​

• “I am also a nurse, so I have always had firsthand examples of illness available to me. That said, life is tough enough as it is, who wants a vaccine-preventable illness on top of everything else? Working with people who are not able to be vaccinated for medical reasons makes me grateful for herd immunity. We, as a community, want the best for each other. What better way to say ‘I care’?”   —Victoria Reierson, Mom
• “I vaccinate, because I truly feel it takes a whole village to raise a child. I’m not only protecting my child but also those around her.”   —Cassie Thompson, Mom
• “I vaccinate not only to protect the health and future of my wonderful boy but to protect the vulnerable in my community. The very young and the old need us to protect them against these awful, sometimes fatal, illnesses. I tell him it’s like the sheriff putting up a wanted poster so his body knows what the bad guys look like and can fight them off as soon as it sees them.”   —Victor Lewis, Dad
• “We love to travel. I do not want to worry about my children contracting an infectious disease in the US and then exposing other people to it overseas. Likewise, I don’t want my children bringing infectious diseases from another country back home either. We have a social obligation to our neighbors, co-workers, and classmates not to expose them to preventable illnesses.”   —Amy Warren, Mom
• “Vaccinating is just one of many ways that I strive to give my kids the best possible chance for healthy and happy lives. Plus, it’s the responsible thing to do for others who are too young for vaccines or who have compromised immune systems.”   —Heather Cooper, Mom
• ​”We vaccinate our children, one of whom is autistic, because we want to protect them from preventable diseases that can have a long-lasting impact on their health. We trust the science and research behind routine immunizations. We also want to protect the members of our community with compromised immune responses, people for whom vaccines aren’t effective, or people who aren’t eligible to receive a certain vaccine.”   —Sandra Turner, Mom
• “I vaccinate, because I had a brother with childhood cancer. When I was young, we had to be so careful all the time to make sure he didn’t get sick. A vaccine-preventable disease would have killed him. I vaccinate for all the other people who are at risk for serious complications from vaccine-preventable illnesses. It’s our job to protect the most vulnerable members of our society.”   —Allison Alexander, Mom

I trust my baby’s doctor.  

• “I vaccinate, because I trust science and I trust my doctors. If we have an opportunity to get rid of a disease forever, we should do everything we can for that to happen. My daughter and future children will be vaccinated according to the AAP’s recommendations.”  —Sarah Wojtovich, Mom 
• “The primary reason I vaccinate my children is because it is recommended by my pediatrician whom I trust. Our pediatrician’s practice sees hundreds of children day in, day out and have children of their own, not to mention years of medical training and expertise.”    —Anne Lee, Mom
• “My wife and I vaccinate our children, because we trust science. We trust the scientific method and we trust the overwhelming amount of doctors who recommend vaccination. There is no possible way we can know everything as a parent, so there have to be authorities which we can trust. I love my children too much to place their safety in anything else but science and logic. We don’t want them to contract viruses nor do we want our children spreading viruses to other children.”   —Travis Harmon, Dad
• “A quick needle poke is much less damaging to an otherwise happy, healthy life than measles, mumps, polio, etc. By vaccinating, we are most definitely protecting those who need extra security. We vaccinate, because we trust our doctors. We trust science. We trust research. We trust the experts. Thank you biologists, researchers, doctors, nurses, and all others who are helping eradicate diseases.”   —Lisa Giles, Mom
• “In a nutshell, I trust my pediatrician and the overall guidance of the AAP. I believe thorough testing has been done to ensure they are safe and that getting vaccinated is safer than not getting vaccinated.”   —Stacy Cordero, Mom
• “Science has proven through much research and study that vaccinating is the best choice to make! Plus, it’s recommended by my pediatrician.”   —Christy Lee, Mom
• “While I do educate myself about my children’s health concerns so that I can be an active participant in their health care, I also trust their pediatrician and the medical community as a whole to be the experts. Being informed does not mean being at odds!”   —Christie Jett, Mom

I want to protect my baby’s body. 

• “We know first-hand the stress that comes with hoping that a very small child doesn’t get very sick. My son was born with a congenital heart defect and spent time in the NICU and later in the hospital after surgery —all during flu season—all before he was more than 3 months old. My daughter, who was only 14 months old when her brother was born, was not only vaccinated, but learned a great deal about handwashing and other healthy habits, because we all had to do our best to protect our little one.”   — Sara Nolan, Mom ​ 
• “When I reached the age of 3, I had high fever and was diagnosed with meningitis. I was given 72 hours to live if the fluid couldn’t get removed. Thanks to quick actions by the medical team, I am now 36 and live a healthy life. I wouldn’t want something like that to happen to my child. If a vaccine would save my child’s life…why not?”   —Joeti Shrestha, Mom​

• “I vaccinate my children to protect them from contracting a debilitating disease that could impact their entire life. My thought has always been, ‘Why would I want to take the chance if a 3-second shot will protect them?’ I had chickenpox and measles as a child; my kids are not missing anything by not having them!”   —Tracy LaPointe, Mom
• “As a parent and provider, I vaccinate. I have seen too many preventable illnesses and death. There is strong evidence that shows vaccines are safe and clearly worth the effort. As far as I am concerned, there is no reason not to vaccinate.”   —Ann Petersen-Smith, Mom 
• “I vaccinate my children (one daughter and twin boys), because I believe passionately in furthering public health. I also believe in the power of science to better our lives. My grandfather was crippled by polio as a child, and while he still leads a happy and productive life, it is tangibly different from the life he would have led without his disability. I know that other children affected with polio and other preventable diseases are not so lucky.”   —Christie Jett, Mom
• “As a nurse in a traveler’s clinic, it breaks my heart to hear from the travelers’ tales of children who have died from tetanus or other vaccine preventable diseases. I cared for the last iron lung patient in my city, and if you need a reason to vaccinate against polio, there it is. It is not a life one would wish for their child.”   —Cindy Ruma, Mom

​​Jenna and Curtis Ehler have fiercely guarded their son’s health since his premature birth nearly two years ago. The couple’s initial excitement over Jenna’s pregnancy had turned to concern in August 2014, when an ultrasound revealed more than they expected.

“The doctor, after seeing the ultrasound said, ‘Oh, surprise!’ And then, ‘Oh, surprise again!” Jenna said. She was carrying triplets, the result of a natural conception. “This pregnancy just went to extremely high-risk,” the doctor told her.

At 24 weeks, Jenna went into early labor and delivered three boys, Gabriel, Caleb and Joshua.

Medical complications took the lives of Gabriel and Caleb within a few days. The lone survivor, Joshua, battled pneumonia, slow heartbeat, chronic lung disease and apnea during his 163-day stay in a Neonatal Intensive Care Unit.

While coping with the devastating deaths of their boys, the couple turned their attention to Joshua. Around his third week, doctors told his parents that they weren’t sure he was going to make it.

 “We rushed to the hospital and tried to prepare ourselves for it,” said Jenna, a librarian from West Des Moines, Iowa. “But, he pulled through. It was really touch and go.”

When Joshua was finally discharged from the hospital, the family spent five months in isolation, allowing only close family members to visit. The couple has kept the baby home much of this winter, as well, concerned after seeing four other children – also born prematurely — hospitalized with a virus.

Jenna worries about Joshua, who turns 2 this summer and has a weakened immune system. He had a cold in December that lasted eight weeks, his mother said.

“We live in a community where there are people who choose not to vaccinate,” said Jenna, 30, who recalled the news about the measles outbreak at Disneyland.

The couple decided against bringing the child to church because of fears that he would be at risk. When the issue came up on a Facebook page, Curtis decided to chime in, she said.

“When you make this choice, it affects my child,” said Jenna, recalling her husband’s response. “It’s not just a decision about your child. Anyone with a suppressed immune system is vulnerable.”

She and her husband were vaccinated as children. She believes that many people her age do not know what it was like to live with diseases like polio.

“My generation, we don’t know what it was like to be really sick because we were all vaccinated,” Jenna said. “In our community of friends, anyone who has experienced a medical trauma tends to support vaccines.”

Jenna had not given deep thought to vaccinations before her family’s tragic loss, and Joshua’s ongoing medical risks.

“It is certainly more real now.”​

​​Maureen Schilling never thought twice about vaccinating her children.

At 46, the Indianapolis mom has suffered from lifelong asthma, severe and persistent allergies and a weak immune system that her family doctors believe stem from a childhood case of measles and resulting complications.

“My husband teases me, ‘Every time a germ floats by, you’re going to get it’,” said Schilling, who has been hospitalized twice for pneumonia. “What I know about it is only what my mother and grandmother were able to tell me—it sounds like the worst possible scenario you could have.”

At 7 months old, she came down with a high fever, and was “spotted and raw all over and dehydrated,” she said. During a lengthy hospital stay, she had a severe allergic reaction to an antibiotic, which resulted in anaphylaxis, a life-threatening condition. She had stopped breathing before she was given a shot of Epinephrine to counteract the reaction.

At age 4, she had her tonsils and adenoids removed and tubes put in her ears. Meanwhile, her sister, who had all the vaccinations available, including the measles vaccine, was a much healthier child, she said.

Her experiences shaped her view on vaccines, prompting her to keep her children up to date with immunizations. Her daughter, 20, and son, 23, left for college with the recommended boosters.

Schilling worries about how easy it is for diseases to spread worldwide. She fears the consequences if people stop vaccinating their children.

“I don’t want to live in a world where polio, measles, rubella, small pox and such deadly diseases make a comeback.” ​​

The American Academy of Pediatrics (AAP) believes that immunizations are the safest and most cost-effective way of preventing disease, disability, and death. We urge parents to make sure that their children are immunized against dangerous childhood diseases since it is always better to prevent a disease than to have to treat it or live with the consequences of having it.

Some children have weakened immune systems because of chronic diseases or medications they’re taking. These include

• Children born with abnormalities of the immune system
• Children infected with human immunodeficiency virus, which causes acquired immunodeficiency syndrome (AIDS), including those who have full-blown AIDS
• Children who have cancer
• Children who have had organ transplants
• Children with diseases that require them to take certain medicines, including corticosteroids

If your child falls into one of these categories, your pediatrician may decide that the benefits of giving certain vaccines outweigh the risks that your youngster’s immune system problems pose. Your doctor also may choose to wait until your child’s immune system is stronger before giving these vaccines.

Here are a few points to keep in mind and discuss with your doctor.

• For a child with a weakened immune system, your pediatrician may suggest delaying or not using immunizations containing live viruses in particular because of the risk of serious effects from the vaccine. These include vaccines such as measles-mumps-rubella (MMR), chickenpox (varicella), and the nasal spray influenza vaccine. (Although the oral polio vaccine contains a live virus, it is no longer used in the United States.) If a child has had chemotherapy, live-virus vaccines are often given 3 months or more after the treatment is completed.
• In general, vaccines with inactivated viruses and bacteria can be used in children who have weakened immune systems with no increased risk. However, the effectiveness of these immunizations can vary in these children and may be reduced in some cases. Vaccines with inactivated viruses or parts of bacteria that do not have an increased risk of side effects in children with weakened immune systems include diphtheria, tetanus, and acellular pertussis; hepatitis A; hepatitis B; polio; Haemophilus influenzae type B; pneumococcal; meningococcal; and the killed influenza vaccines (those given by shot).
• Children taking corticosteroids can have weakened immune systems. The decision of whether to use vaccines in these youngsters often depends on the dose of steroids taken, as well as how these medicines are given. For example, when steroids are given in the form of topical medicines (applied directly to the skin), or if they’re inhaled in an aerosol formulation (often to treat asthma or allergies), they don’t interfere with the immune system. This means live-virus vaccines can be given to these youngsters. Also, children taking steroid pills in low or moderate doses can safely be given live-virus vaccines.

Grade-school–aged kids and teens need a number of vaccines to protect them.

The vaccines recommended for kids at around age 9 years until they graduate from high school help prevent major health problems, including infertility, muscle paralysis, brain damage, blindness, deafness and cancer.

The American Academy of Pediatrics (AAP), Centers for Disease Control and Prevention (CDC) and other medical groups all agree on the schedule of recommended immunizations. They recommend these vaccines at specific ages. Why? There are two main reasons:

• It is the age when the vaccine works the best with your child or teen’s immune system.
• It is the time when your child or teen needs the protection the most.

Because of the pandemic, teens may have fallen behind on some of their immunizations. It is important for them to see their pediatricians. That way they can make sure they are up to date and fully protected.

Here’s what to know about the vaccines recommended for preteens, teens and young adults, and the diseases they prevent

Meningococcal: At age 11 or 12, your teen should get their first meningococcal vaccine. There are two kinds of vaccines to protect against meningococcus.

• Meningococcal conjugate vaccine protects against 4 types of bacteria which are labeled with the letters A, C, W and Y. Teens get their first dose of this at age 11 or 12 and a booster at age 16.
• Meningococcal type B vaccine is another type of meningococcal vaccine. It protects against a different type of the bacteria. This vaccine is available for teens age 16 to 18 years. Men B vaccine is recommended for kids who have certain chronic health conditions that make them more vulnerable or those who may be in an area where there’s an outbreak. So, it’s a good idea to talk with your pediatrician about this vaccine, too, if your teen didn’t get other vaccines when they were younger.

Meningococcal: A fast-acting disease

Meningococcal vaccines are given in high school to protect teens from meningococcal disease. The disease is life-threatening if it’s not caught and treated early—within a few hours. The disease is caused by bacteria that can affect the bloodstream, brain and spinal cord—and it preys on people between the ages of 15 and 21. Every year, about 1,000 people in the U.S. get meningococcal disease. Infections spread easily in crowded places, especially among high school and college students who live in dorms. Getting the first dose of the vaccine at age 11 and the second dose at age 16 before college protects teens when they’re most vulnerable.

Tetanus, diphtheria and pertussis: At age 11 or 12, we give a vaccine called Tdap. This vaccine is a booster to protect against three diseases: tetanus, diphtheria and pertussis (whooping cough). It’s a slightly different version of a vaccine your child received as a baby (DTaP). The version for teens and adults has a different name because it has lower doses of the diphtheria and pertussis vaccines. (It has the same amount of tetanus vaccine, though.) After your child gets Tdap vaccine at age 11 or 12, they will need a booster every 10 years as an adult as well.

• Tetanus is a type of bacteria that naturally lives in the soil or dust. You can be exposed to it through any break in your skin like a cut or puncture wound. Tetanus produces a deadly toxin that causes painful muscle contractions. Another name for tetanus is lockjaw, because it often causes a person’s neck and jaw muscles to lock making it hard to open the mouth or swallow. We will never eliminate this bacterium from our world, so the vaccine is the best way to prevent tetanus.
• Diphtheria is a disease that causes a serious throat infection, breathing problems and heart failure. Before we had a vaccine, diphtheria killed 1 out of every 5 kids who were infected. The vaccine is a lifesaver.
• Pertussis (whooping cough) can cause a cough that won’t go away, and sometimes causes vomiting or trouble breathing. The protection your teen got from their childhood vaccine starts to wear off around age 11. That is why a booster is so important. Teens can easily spread the disease to others, including infants, who are at even more risk.

Human papillomavirus (HPV): The HPV vaccine prevents cancer in males and females. The vaccine works better with a child’s immune system at age 9-12, so they need just 2 doses. If they don’t get the first dose until age 15, they need 3 shots.

• HPV causes cervical cancer, penile and anal cancers, cancers of the mouth and throat, and genital warts. The HPV vaccine works really well to protect against strains of the virus that cause more than 90% of these cancers.

Influenza (flu): The AAP and the CDC recommend the flu shot for everyone age 6 months and older, including teens, every year. The flu is unpredictable. There is no way to know if your teen will have mild flu illness and miss just a few days of school or if they will get seriously ill and need hospital care. The flu shot is very effective at preventing severe influenza disease that leads to hospitalization.

Behind on other vaccines?

Now is the time to catch up on recommended immunizations that your teen may have missed. That includes hepatitis A, hepatitis B, polio, pneumococcal vaccine, the measles-mumps-rubella (MMR) vaccine and the chickenpox (varicella) vaccine.

Heading off to college? Some colleges and universities require students to be vaccinated. Check these requirements now, so your teen can be caught up before they go.

Remember

These recommended vaccines are the best way to protect teens and give parents peace of mind. Many of them can literally save your teen’s life! Sure, getting a shot may hurt for a moment—but the protection from serious disease lasts a very long time.

​Some people have concerns about vaccine safety. The fact is vaccines save millions of lives and protect EVERYONE against the spread of disease. If you decide not to vaccinate your child, you’re putting them at risk of catching a disease that is dangerous or even deadly. You’re also putting others who have contact with your child at risk. Getting vaccinated is much better than getting the disease.

In fact, some of the worst diseases that affect children have been greatly reduced or eliminated completely thanks to vaccines. Today, vaccines protect children and teens from 16 of these diseases.
Vaccines protect children from deadly diseases like:
Polio, measles, rubella, mumps, chickenpox, meningitis, pneumonia, tetanus (lock jaw), hepatitis A and B, influenza, diarrheal infections, reproductive cancers and more.

Your pediatrician knows that you care about your child’s health and safety. And your pediatrician cares about your child, too. That’s why it’s important to get all the scientific facts from a medical professional you can trust. It’s best not to make decisions based on stories you may have seen or heard on TV, the internet, or from other parents.

Here’s what your pediatrician wants you to know about vaccinating your child:

1. Vaccines work.

They have kept children healthy and have saved millions of lives for decades. Most childhood vaccines are 90% to 99% effective in preventing disease. And if a vaccinated child does get the disease, the symptoms are usually less serious than in a child who did not get the vaccine and got sick from the disease. Your child may have mild side effects after a shot, like swelling where the shot was given. These side effects don’t last long though. And it is rare for side effects to be serious.

2. Vaccines are safe.

Before a new vaccine is given to people in the United States, it must be reviewed by health experts. This involves several steps.

A vaccine must go through detailed clinical trials before it is approved by the Food and Drug Administration (FDA) for use in children. The trials look at the vaccine’s safety, side effects, and effectiveness. A group of experts called the Vaccines and Related Biological Products Advisory Committee then advises the FDA whether the vaccine should be approved for licensure. The FDA only licenses a vaccine if it is safe and effective, and its benefits are greater than any risks.

Next, if the vaccine is licensed, another group of experts is convened by the CDC, called the Advisory Committee on Immunization Practices (ACIP). This committee makes recommendations on use of vaccines approved by the FDA. The ACIP also advises whether the new vaccine should be added to the Recommended Child and Adolescent Immunization Schedule.

Even after a vaccine is approved and recommended for use, the safety and effectiveness of the vaccine continues to be monitored by the CDC and FDA. This “post-marketing” surveillance allows them to identify any rare side effects that were not able to be detected during the clinical trials.

Cause or coincidence?

The United States takes vaccine safety very seriously. In fact, anyone can report any health problem after they received a vaccine to the Vaccine Adverse Event Reporting System (VAERS), even if the health problem was not caused by the vaccine.
Health care providers, patients or family members can submit reports. Because VAERS is an open system, the reports vary in quality and completeness. They often lack details and can have information that contains errors.
The benefit of this open system is that new, unusual or rare vaccine adverse events can be detected right away.
Remember: VAERS accepts all reports without judging whether the event was caused by the vaccine. No proof that the event was caused by the vaccine is required before the report is accepted.

3. Vaccines boost natural immunity

It is reasonable to think that natural immunity is all your child needs. Babies are born with immune systems that can fight many germs. And when infants are breastfed, they get added protection from minor illness like colds. This protection does not last long, though.

Sometimes, one or two doses of a vaccine can teach your child’s immune system how to respond to an infection for a lifetime. What if our immune system forgets how to get rid of the infection over time? That is when our immune system needs to be reminded. This is referred to as giving “booster shots.” Booster shots are just as important as your child’s first vaccinations. They refresh your child’s immune system memory by building on the instructions learned from the previous vaccines. If booster shots are missed, the child’s immune system has less memory to respond when they are infected with the vaccine-preventable illness.

4. Vaccines are necessary.

Your pediatrician knows that your child should receive all recommended childhood vaccines. In many parts of the world, vaccines are not as commonly available.

Diseases that are rarely seen in the U.S. can still be brought into the country by people visiting areas with current disease outbreaks. This is another reason why it’s important that your child is fully vaccinated. Being vaccinated will protect your child but also help to protect others in the community. This protection of the community is commonly referred to as herd immunity.

When enough people are vaccinated, everyone receives some protection from the spread of diseases. This includes those who are unable to be immunized (such as children who are too young or others who are immunocompromised). But relying on herd immunity to keep your child safe is risky. And, if our vaccination rate drops too low, vaccine-preventable infections will return. We have seen that many times in the past few years with outbreaks of whooping cough, measles and mumps.

​​​​The safety an​d effectiveness of vaccines​ are under constant study. Because vaccines are designed to be given routinely during well-child care visits, they must be extraordinarily safe. Safety testing begins as soon as a new vaccine is contemplated, continues until it is licensed, and is monitored indefinitely after licensure. 

The American Academy of Pediatrics (AAP) works closely with the Centers for Disease Control and Prevention (CDC) to make recommendations for vaccine use.

Over the past decade, questions have been raised regarding a relationship between autism and vaccines. Along with general safety concerns, parents have wondered about:

• Too many vaccines overwhelming the immune system
• The measles, mumps, rubella combination vaccine (MMR)
• The preservative thimerosal, which was never present in MMR but was present in several vaccines used in the 1990s—it has since been removed from all routinely used childhood vaccines with the exception of flu.

Research has been conducted on all of these topics, and the studies continue to find vaccines to be a safe and effective way to prevent serious disease.

This article lists those studies and provides links to the publications to allow parents—and all those who administer or recommend vaccines—to read the evidence for themselves. These studies do not show any link between autism and MMR vaccine, thimerosal, multiple vaccines given at once, fevers or seizures. Note: This is not an exhaustive list—vaccine safety studies are constantly being conducted and published and may not be reflected here.

Please examine the evidence for yourself. If you have any questions, speak with your pediatrician​.

Studies About General Safety & Number of Vaccines

​Study	​Summary	​Author Conclusion
​Association Between Estimated Cumulative Vaccine Antigen Exposure Through the First 23 Months of Life and Non–Vaccine Targeted Infections From 24 Through 47 Months of Age Glanz J, et al. JAMA. 2018; 319(9):906-913.	​Authors looked at whether there was a connection between acquiring an infection that is not targeted by vaccines (meaning there is no vaccine to prevent this illness) and exposure to antigens through vaccines. Nine hundred ninety-four children were studied from age 24 months to age 47 months. Of those, 193 were seen in an emergency department for an infection that was not targeted by vaccines, and 751 children acquired no such infections. Authors then counted the number of antigens to which children were exposed through vaccines. Children who developed non-vaccine targeted infections had been exposed to an average of 240.6 antigens from vaccines and children who did not develop such infections had been exposed to an average of 242.9 antigens from vaccines.	​There is no significant correlation between exposure to antigens through vaccines and risk of developing a non-vaccine targeted infection.
​Vaccines Are not Associated with Autism: An Evidence-based Meta-analysis of Case-control and Cohort Studies Taylor L, Swerdfeger A, Eslick G. Vaccine. 2014; 32: 3623-9.	​Authors of this article reviewed 10 studies (5 cohort and 5 case-control), involving over 1.25 million children to determine if a relationship between autism spectrum disorders (ASDs) and vaccines, MMR vaccine, thimerosal or mercury existed. While these 10 individual studies had not found relationships between MMR, mercury or thimerosal, and ASD, authors combined and analyzed the data from the 5 cohort studies and did the same for the 5 case-control studies.	​After performing the meta-analysis of both the five cohort studies and the five case-control studies, authors found no evidence of a link between vaccine receipt and risk of developing autism or ASDs. This conclusion stands when authors looked at specific MMR vaccines, cumulative mercury dosage, and thimerosal exposure, and any connection to ASDs.
​Increasing Exposure to Antibody-Stimulating Proteins and Polysaccharides in Vaccines Is Not Associated with Risk of Autism DeStefano F, Price, C, Weintraub E. The Journal of Pediatrics. 2013; 163(2): 561-567.	​Researchers identified 321 children who had been diagnosed with either autism spectrum disorder (ASD), autistic disorder (AD) or ASD with regression and matched them with 752 children who did not have these conditions and were suitable controls. Then researchers compared the number of antibody-stimulating proteins and polysaccharides, to which these two groups of children had been exposed from vaccines during 3 periods, birth to 3 months, birth to 7 months and birth to 2 years. These comparisons were to determine whether children with ASD, AD, or ASD with regression diagnoses were exposed, on average, to more antigens.	​There was no evidence of a connection between exposure to antibody-stimulating proteins and polysaccharides from vaccines during the first 2 years of life and the risk of an ASD, AD, or ASD with regression diagnosis. Furthermore, there was no evidence of associations when exposures were assessed from birth to 3 months, from birth to 7 months, from birth to 2 years, or when comparing a maximum number of exposure in one day.
​Number of antigens in early childhood vaccines and neuropsychological outcomes at age 7-10 years Iqbal S, Barile JP, Thompson WW, DeStefano F. Pharmacoepidemiology and Drug Safety. 2013; 22(12):1263-70.	​Authors provided standardized tests to 1,107 children ages 7-10 years. These tests aimed to evaluate the following:Domain-specific neuropsychological outcomes General intellectual function Speech and language Verbal memory Attention and executive function Tics Achievement Visual spatial ability Behavior regulation Through historical, records, authors counted the number of antigens children received through vaccines, by ages 7 months, 12 months and 24 months.  The tests results were compared with the average number of antigens to which the children were exposed at each age studied.	​There were no adverse associations between antigens received through vaccines during the first two years of life and neuropsycholcogical outcomes tested at age 7-10 years.
The Childhood Immunization Schedule and Safety Stakeholder Concerns, Scientific Evidence, and Future Studies Hinshaw A, et al. Institute of Medicine. The National Academy of Sciences. 2013.	The Institute of Medicine acquired feedback from many affected by vaccines including parents, healthcare providers, researchers and many more. They learned, that even though more than 90% of children entering kindergarten have received most recommended vaccines, there are gaps in the communication between providers and parents about vaccine safety. Some parents feel the vaccine schedule is too crowded, and desire to have vaccines given over a longer period of time. Others seems to dismiss the well-documented benefits of vaccines and fear potential side effects (even those that are not scientifically linked to vaccines). These concerns lead to some parents not vaccinating their children, which in turn leads to outbreaks of diseases.	​Over the previous 40 years the IOM has conducted over 60 vaccine safety studies, including this comprehensive review of the immunization schedule. The IOM committee did not find any evidence of major safety concerns related to receiving on-time vaccinations according to the Recommended Immunization Schedule for children. They concluded that this should help to reassure stakeholders. Further, they noted that while the receiving on-time vaccines was not harmful, it was strongly associated with reducing vaccine-preventable diseases. ​
​Adverse Effects of Vaccines Evidence and Causality  Clayton E, et al. Institute of Medicine. The National Academy of Sciences. 2011	​The Institute of Medicine studied the relationship between 8 types of vaccines (varicella zoster vaccines; influenza vaccines; hepatitis B vaccines; human papillomavirus vaccines; measles, mumps, and rubella vaccine, hepatitis A vaccine, meningococcal vaccines and tetanus-containing vaccines that did not include whole-cell pertussis component [no US vaccine contain the whole-cell pertussis component currently]) and adverse events. ​	​Authors found evidence to accept some causal relationships between vaccines and adverse effects (such as varicella vaccine and varicella infection, or anaphylaxis [severe allergic reaction] and HPV vaccine. They also found evidence to reject a causal relationship between MMR vaccine and autism, MMR vaccine and type I diabetes, and DTaP vaccine and type I diabetes.​
​On-time Vaccine Receipt in the First Year Does Not Adversely Affect Neuropsychological Outcomes Smith M and Woods C, Pediatrics. 2​010; 125(6): 1134-41	​The study of more than 1,000 children born between 1993 and 1997 looked at their vaccination schedules up to 1 year of age, and studied their performance 7 to 10 years later on 42 different neuropsychological outcomes. Timely vaccination was associated with better performance on numerous outcomes. The less-vaccinated children did not do significantly better on any of the outcomes.	​This comparison of children vaccinated on time with children whose vaccinations were delayed or incomplete found no benefit in delaying immunizations during the first year of life. For parents who are concerned that children receive too many vaccines too soon, these data may provide reassurance that timely vaccination during infancy has no adverse effect on long-term neuropsychological outcomes.
​Evaluation of Immunization Rates and Safety Among Children with Inborn Errors of Metabolism Klein N, et al., Pediatrics. 2011; 127(5), e1139-46	​Researchers studied children in Northern California to determine whether 77 infants with inborn errors of metabolism who received vaccines were more likely to experience adverse events following vaccination, than 1540 matched controls (infants born without inborn errors of metabolism).  Authors did not find any association between vaccination of children with inborn errors of metabolism and an increase in hospitalizations or emergency-department visits within 30 days of vaccination. ​	​On-time receipt of vaccines is not associated with increased risk for serious adverse events in the 30 days after vaccination, even in children who have metabolism conditions. This should provide reassurance that children with inborn errors of metabolism who are vaccinated routinely do not experience adverse effects.
​Measles-Containing Vaccines and Febrile Seizures in Children Age 4 to 6 Years Klein N, et al., Pediatrics. 2011; 129(5): 809-14	​Researchers chose to perform cohort study and included 715,484 children aged 48-83 months of age who received a dose of MMRV, a dose of MMR on the same day as a dose of Varicella injected separately, or MMR alone or Varicella alone to determine the risk of post-vaccination seizure in these groups. Results showed that more fevers and seizures did occur in children who had received the MMRV vaccine, compared with children who had received MMR + Varicella, or MMR or Varicella separately, though this finding was not statistically significant. The study did not find any peak in seizure or fever activity in any of the study groups in the 7-10 post-vaccination period. Of the 4 febrile seizures observed in the 7-10 days in the post-vaccination period for children receiving MMRV, only one febrile seizure could be confirmed, resulting in authors claiming the rate of febrile seizure after MMRV to be 1 in 86,750 doses.	​Overall researchers found no increased risk of febrile seizures in any of the study groups within 6 weeks ​of vaccination. ​

Studies Looking at the Measles, Mumps, and Rubella (MMR) Vaccine

​

​​Study	​Summary	​Author Conclusion
​Autism Occurrence by MMR Vaccine Status Among US Children with Older Siblings with and Without Autism Jain A, et al. JAMA. 2015; 313(5): 1534-40.	​This study identified a cohort of children with older siblings. Some siblings had been diagnosed with autism spectrum disorder (ASD) and some children in the cohort had received an ASD diagnosis. Authors calculated the relative risk (RR) of a child receiving an ASD diagnosis at ages 2 years, 3 years or 4 years based on whether the child had received 0 or 1 dose of MMR vaccine, AND whether the child had a sibling with ASD or a sibling without ASD. They also calculated the RR of a child receiving an ASD diagnosis at age 5 years based on whether they received 0, 1 or 2 doses of MMR vaccine and whether they had a sibling with ASD or a sibling without ASD.	​Authors found no association between MMR vaccination and increased ASD risk and no evidence that receipt of 1 or 2 doses of MMR vaccine was association with a raised risk of ASD for children with had an older sibling with ASD.
​No Evidence for Measles, Mumps, and Rubella Vaccine-Associated Inflammatory Bowel Disease or Autism in a 14-year Prospective Study Peltola H, et al., Lancet. 1998; 351:1327-8	​Prospective study of 3 million adverse events in temporal relation to MMR vaccine. A form was filled and posted to the data collectors, followed by another form with further information 2-3 weeks later. Researchers traced subjects who developed gastrointestinal symptoms or signs lasting 24 hours or more at any time after MMR vaccination (apart from within the first hour). Researchers also checked hospital and health center records or interviewed the local public-health nurses.	Over a decade’s effort to detect all severe adverse events associated with MMR vaccine could find no data supporting the hypothesis that it would cause pervasive developmental disorder or inflammatory bowel disease.
​Autism and Measles, Mumps, and Rubella Vaccine: No Epidemiological Evidence for a Causal Association Taylor B, et al., Lancet. 1999; 353(9169): 2026-9	​Researchers looked for a change in trend in incidence or age at diagnosis associated with the introduction of MMR vaccination to the United Kingdom in 1988. The study identified 498 cases of autism (261 of core autism, 166 of atypical autism, and 71 of Asperger syndrome) in children born in the UK since 1979. There was a steady increase in cases by year of birth with no sudden “step-up” or change in the trend line after the introduction of MMR vaccination. There was no difference in age at diagnosis between the cases vaccinated before or after 18 months of age and those never vaccinated. There was no temporal association between onset of autism within 1 or 2 years after vaccination with MMR. Developmental regression was not clustered in the months after vaccination.	​Data do not support a causal association between MMR vaccine and autism. If such an association occurs, it is so rare that it could not be identified in this large regional sample.
​Mumps, Measles, and Rubella Vaccine and the Incidence of Autism Recorded by General Practitioners: A Time Trend Analysis Kaye JA, et al., British Medical Journal. 2001; 322:460-63	​Study compared prevalence of MMR vaccination among children in the United Kingdom to rising prevalence of autism diagnoses for children.	​The data provide evidence that no correlation exists between the prevalence of MMR vaccination and the rapid increase in the risk of autism over time.​
​MMR and autism: further evidence against a causal association Farrington CP, et al., Vaccine. 2001; Jun 14; 19(27): 3632-5	​Data from an earlier MMR vaccine study (Taylor et al, 2000) were reanalyzed to test a second hypothesis.	​Results provide further evidence against a causal association between MMR vaccination and autism.
​Time Trends in Autism and in MMR Immunization Coverage in California Dales L et al., Journal of the American Medical Association. 2001; 285(9): 1183-5	​Scientists looked for correlation between increases in the rate of autism diagnoses and increases in the rate of MMR vaccination in children born between 1980 and 1994.	​These data do not suggest an association between MMR immunization among young children and an increase in autism occurrence.
​Measles-Mumps-Rubella and Other Measles-Containing Vaccines Do Not Increase the Risk for Inflammatory Bowel Disease: A Case-Control Study from the Vaccine Safety Datalink Project Davis RL, et al., Archives of Pediatric and Adolescent Medicine. 2001;155(3): 354-9	​A case control study of 155 persons with inflammatory bowel disease with up to five controls each. Neither past vaccination nor age at vaccination with other MCV was associated with increased risk for Crohn’s disease, ulcerative colitis, or IBD. Risk for Crohn’s disease, ulcerative colitis, or IBD was not elevated in the time immediately following vaccination with either vaccine.	​Vaccination with MMR or other MCV, or the timing of vaccination early in life, did not increase the risk for IBD.
​No Evidence for a New Variant of Measles-Mumps-Rubella-Induced Autism Fombonne E, et al., Pediatrics. 2001; 108(4): e58	​Study compared 96 children with a pervasive developmental disorder (PDD) born between 1992 and 1995 and who had received the MMR vaccine, to PDD patients who did not receive MMR.	​No evidence was found to support a distinct syndrome of MMR-induced autism or of “autistic enterocolitis.” These results add to the large-scale epidemiologic studies that all failed to support an association between MMR and autism at population level. These findings do not argue for changes in current immunization programs and recommendations.
​Measles, Mumps, and Rubella Vaccination and Bowel Problems or Developmental Regression in Children with Autism: Population Study Taylor B, et al. British Medical Journal. 2002; 324(7334): 393-6	​Population study of 278 children with core autism and 195 with atypical autism, born between 1979 and 1998. The proportion of children with developmental regression (25% overall) or bowel symptoms (17%) did not change significantly during the 20 years from 1979, a period which included the introduction of measles, mumps and rubella (MMR) vaccination in October 1988.	​Data provide no support for an MMR associated “new variant” form of autism with developmental regression and bowel problems, and further evidence against involvement of MMR vaccine in the initiation of autism.
​Relation of Childhood Gastrointestinal Disorders to Autism: Nested Case Control Study Using Data from the UK General Practice Research Database​Black C, et al., British Medical Journal. 2002; 325: 419-21	​Nested case control study of 96 children diagnosed with autism and 449 controls. The estimated odds ratio for a history of gastrointestinal disorders among children with autism compared with children without autism was 1.0 (95% confidence interval 0.5 to 2.2). ​	​No evidence was found that children with autism were more likely than children without autism to have had defined gastrointestinal disorders at any time before their diagnosis of autism.
​Neurologic Disorders after Measles-Mumps-Rubella Vaccination​ Makela A, et al., Pediatrics. 2002; 110: 957-63​	​Study of 535,544 1- to 7-year-old children who were vaccinated between November 1982 and June 1986 in Finland.	​Data do not support an association between MMR vaccination and encephalitis, aseptic meningitis or autism.
​A Population-Based Study of Measles, Mumps, and Rubella Vaccination and Autism Madsen KM, et al., New England Journal of Medicine. 2002; 347(19): 1477-82	​Compared relative risk of ASD in children vaccinated with MMR vaccine and unvaccinated children born in Denmark between 1991 and 1998. Of the 537,303 children in the cohort, 82% had received the MMR vaccine. Researchers identified 316 children with a diagnosis of autism and 422 with a diagnosis of other ASDs. There was no association between the age at the time of vaccination, the time since vaccination, or the date of vaccination and the development of autism.	​This study provides strong evidence against the hypothesis that MMR vaccination causes autism.
​Prevalence of Autism and Parentally Reported Triggers in a North East London Population Lingam R, et al., Archives of Disease in Childhood. 2003; 88(8): 666-70	​Study of reported age of onset of ASD among 567 children in northeast London born between 1979 and 1998. The age at diagnosis of ASD was estimated to have decreased per five-year period since 1983, by 8.7% for childhood autism and by 11.0% for atypical autism. There was some evidence that MMR vaccine was more likely to be mentioned as a trigger after August 1997 than before.	​The data suggest that a rise in autism prevalence was likely due to factors such as increased recognition, a greater willingness on the part of educators and families to accept the diagnostic label, and better recording systems. The proportion of parents attributing their child’s autism to MMR appears to have increased since August 1997.
​MMR Vaccination and Perva​sive Developmental Disorders: A Case-Control Study Smeeth L, et al., Lancet 2004; 364(9438): 963-9​	​Matched case-control of 1,295 people born in 1973 or later who had first recorded diagnosis of pervasive developmental disorder while registered with a contributing general practice between 1987 and 2001. Controls (4,469) were matched on age, sex and general practice. 1,010 cases (78.1%) had MMR vaccination recorded before diagnosis, compared with 3,671 controls (82.1%) before the age at which their matched case was diagnosed.	​Data suggest that MMR vaccination is not associated with an increased risk of pervasive developmental disorders.
​Age at First Measles-Mumps-Rubella Vaccination in Children with Autism and School-Matched Control Subjects: A Population-Based Study in Metropolitan Atlanta DeStefano F et al., Pediatrics 2004; 113(2): 259-66	​Study compared ages at first MMR vaccination between children with autism and children who did not have autism in the total population and in selected subgroups, including children with regression in development.	​Similar proportions of case and control children were vaccinated by the recommended age or shortly after (i.e., before 18 months) and before the age by which atypical development is usually recognized in children with autism (i.e., 24 months).​
​No evidence for links between autism, MMR and measles virus Chen W, et al., Psychological Medicine. 2004 April; 34(3): 543-53	​Study compared 2,407 persons with autism born between 1959 and 1993; to 4,640 Down syndrome subjects born between 1966 and 1993.	​No increased risk of autism was found following exposures to wild measles and vaccinations with monovalent measles, and Urabe or Jeryl-Lynn variants of MMR vaccine.
​No effect of MMR withdrawal on the incidence of autism: a total population study Honda H, et al., Journal of Child Psychology and Psychiatry. 2005; 46(6): 572-9​	​Study examined incidence of ASD to age 7 for children born between 1988 and 1996 in Yokohama, Japan. The MMR vaccination rate in Yokohama declined significantly in the birth cohorts of years 1988-92, and no MMR vaccines were administered in 1993 or thereafter. In contrast, cumulative incidence of ASD up to age 7 increased significantly in the birth cohorts of years 1988 through 1996 and most notably rose dramatically beginning with the birth cohort of 1993.	​MMR vaccination is not likely to be a main cause of ASD, and cannot explain the rise over time in the incidence of ASD. Withdrawal of MMR in countries where it is still being used cannot be expected to lead to a reduction in the incidence of ASD.
​Immunization Safety Review: Vaccines and Autism Institute of Medicine, The National Academies Press: 2004​	​The IOM’s Committee on Immunization Safety Review was convened in the fall of 2000 to provide an independent review of increasingly prominent vaccine safety concerns. The 15 committee members with expertise in pediatrics, internal medicine, immunology, neurology, infectious diseases, epidemiology, biostatistics, public health, risk perception, decision analysis, nursing, genetics, ethics and health communications analyzed over 200 relevant studies.	​The committee rejected a causal relationship between the MMR vaccine and autism as well as a causal relationship between thimerosal-containing vaccines and autism.
​Relationship between MMR Vaccine and Autism Klein KC, Diehl EB.  The Annals of Pharmacotherapy. 2004; 38(7-8):1297-300	​Ten articles that specifically evaluated the possible relationship between the MMR vaccine and autism were identified. Review articles, commentaries, and evaluations of a link between gastrointestinal symptoms in autistic children and MMR immunization were excluded.	Based upon the current literature, it appears that there is no relationship between MMR vaccination and the development of autism.
​Is There a ‘Regressive Phenotype’ of Autism Spectrum Disorder Associated with the Measles-Mumps-Rubella Vaccine? A CPEA Study Richler, et al., Journal of Autism and Developmental Disorders. 2006; 36(3): 299-316	​A multi-site study of 351 children with ASD and 31 typically developing children used caregiver interviews to describe the children’s early acquisition and loss of social-communication milestones. For the majority of children with ASD who had experienced a regression, pre-loss development was clearly atypical.	​No evidence that onset of autistic symptoms or of regression was related to measles, mumps and rubella vaccination.
​Pervasive Developmental Disorders in Montreal and Quebec, Canada: Prevalence and Links with Immunizations Fombonne E, et al., Pediatrics. 2006; 118(1): e139-50	​Study of thimerosal and MMR vaccine uptake in 28,000 Canadian children born between 1987 and 1998, of whom 180 were identified with a pervasive developmental disorder.	​The data rule out an association between pervasive developmental disorder and either high levels of ethyl mercury exposure comparable with those experienced in the United States in the 1990s or 1- or 2-dose MMR vaccinations.
​Immunizations and Autism: A Review of the Literature Doja A, and Roberts W, The Canadian Journal of Neurological Sciences. 2006; 33(4): 341-6​	​Literature review found very few studies supporting an association between vaccines and autism, with the overwhelming majority showing no causal association between the measles, mumps and rubella (MMR) vaccine and autism. The vaccine preservative thimerosal has alternatively been hypothesized to have a possible causal role in autism.	No convincing evidence was found to support an association between the vaccine preservative thimerosal and autism, nor for the use of chelation therapy in autism.​
​No Evidence of Persisting Measles Virus in Peripheral Blood Mononuclear Cells from Children with Autism Spectrum Disorder D’Souza Y, et al., Pediatrics. 2006; 118(4): 1664-75. ​	​Peripheral blood mononuclear cells were isolated from 54 children with ASD and 34 developmentally normal children, and up to 4 real-time polymerase chain reaction assays and 2 nested polymerase chain reaction assays were performed. No sample from either ASD or control groups was found to contain nucleic acids from any measles virus gene. In the nested polymerase chain reaction and in-house assays, none of the samples yielded positive results. Furthermore, there was no difference in anti-measles antibody titers between the autism and control groups.	​There is no evidence of measles virus persistence in the peripheral blood mononuclear cells of children with ASD.
​MMR-Vaccine and Regression in Autism Spectrum Disorders: Negative Results Presented from Japan Uchiyama T, et al., Journal of Autism and Developmental Disorders. 2007; 37(2): 210-7	​Study of 904 patients with ASD. During the period of MMR usage, no significant difference was found in the incidence of regression between MMR-vaccinated children and non-vaccinated children. Among the proportion and incidence of regression across the three MMR-program-related periods (before, during and after MMR usage), no significant difference was found between those who had received MMR and those who had not. Moreover, the incidence of regression did not change significantly across the three periods.	​The data do not support an association between MMR and autism.
​Measles Vaccination and Antibody Response in Autism Spectrum Disorders Baird G, et al., Archives of Disease in Childhood. 2008; 93(10): 832-7​	​Case-control study of 98 vaccinated children aged 10-12 years in the UK with ASD and two control groups of similar age: 52 children with special educational needs but no ASD and 90 children in the typically developing group. No difference was found between cases and controls for measles antibody response. There was no dose-response relationship between autism symptoms and antibody concentrations.	​No association between measles vaccination and ASD was shown.
​Lack of Association between Measles Virus Vaccine and Autism with Enteropathy: A Case-Control Study Hornig M et al., PLoS ONE. 2008; 3(9): e3140 ​	​Researchers looked for measles virus in the guts of 25 children with both autism and gastrointestinal disorders, and another 13 children with the same gastrointestinal disorders but no autism. The virus was detected in one child from each group.	​This study provides strong evidence against association of autism with persistent measles virus RNA in the gastrointestinal tract or with MMR vaccine exposure.
​Lack of Association Between Measles-Mumps-Rubella Vaccination and Autism in Children: A Case-Control Study Budzyn D, et al., The Pediatric Infectious Disease Journal. 2010; 29(5): 397-400	​Researchers in Poland compared vaccination history and autism diagnosis in 96 children with autism, ages 2 to 15, as well as 192 children in a control group. For children diagnosed before a diagnosis of autism, the autism risk was lower in children who received MMR vaccine than in nonvaccinated children. A similar result was achieved for the single-antigen measles vaccine.	​The study provides evidence against the association of autism with either MMR or a single measles vaccine.​

Court Decisions

​​Case	​Result
​U.S. Court of Federal Claims decision in Omnibus Autism Proceeding	​On Feb. 12, 2009, the “vaccine court” ruled in three test cases on the theory that MMR vaccine and the vaccine preservative thimerosal are linked to autism. The court found the scientific evidence is overwhelmingly contrary to this theory.

Studies Looking at Thimerosal

​​​Study	​Summary	​Author Conclusion
​Association Between Thimerosal-Containing Vaccine and Autism Hviid, et al., Journal of the American Medical Association. 2003; 290(13):1763-6​	​Study of 467,000 children born in Denmark between 1990 and 1996 compared children who were vaccinated with a thimerosal-containing vaccine to children who received a thimerosal-free formulation of the same vaccine. The risk of autism and other autism spectrum disorders did not differ significantly between children vaccinated with thimerosal-containing vaccine and children vaccinated with thimerosal-free vaccine.	​The results do not support a causal relationship between childhood vaccination with thimerosal-containing vaccines and development of autistic-spectrum disorders.
​Thimerosal Exposure in Infants and Developmental Disorders: A Prospective Cohort Study in the United Kingdom Does Not Support a Causal Association Heron, et al., Pediatrics. 2004;114(3)3: 577-83 ​	​The researchers monitored the thimerosal exposure of more than 14,000 children born in the United Kingdom between 1991 and 1992. The age at which doses of thimerosal-containing vaccines were administered was recorded, and measures of mercury exposure by 3, 4 and 6 months of age were calculated and compared with a number of measures of childhood cognitive and behavioral development covering the period from 6 to 91 months of age.	​No convincing evidence was found that early exposure to thimerosal had any deleterious effect on neurologic or psychological outcome.
​Thimerosal and the Occurrence of Autism: Negative Ecological Evidence From Danish Population-Based Data Madsen, et al., Pediatrics. 2003; 112(3): 604-6​	​Analyzed data from the Danish Psychiatric Central Research Register recording all psychiatric admissions since 1971, and all outpatient contacts in psychiatric departments in Denmark since 1995. There was no trend toward an increase in the incidence of autism during that period when thimerosal was used in Denmark, up through 1990. From 1991 until 2000 the incidence increased and continued to rise after the removal of thimerosal from vaccines, including increases among children born after the discontinuation of thimerosal.	​The discontinuation of thimerosal-containing vaccines in Denmark in 1992 was followed by an increase in the incidence of autism. The data do not support a correlation between thimerosal-containing vaccines and the incidence of autism.
​Autism and thimerosal-containing vaccines: Lack of consistent evidence for an association Stehr-Green P, et al., American Journal of Preventive Medicine. 2003; 25(2):101-6	​Study compared the prevalence/incidence of autism in California, Sweden and Denmark from the mid-80s to the late 90s with average exposures to thimerosal-containing vaccines. In all three countries, the incidence and prevalence of Autism Spectrum Disorders began to rise in the 1985-1989 period, and the rate of increase accelerated in the early 1990s.	​The data is not consistent with the hypothesis that increased exposure to thimerosal-containing vaccines is responsible for the apparent increase in the rates of autism in young children being observed worldwide.
​Thimerosal Exposure in Infants and Developmental Disorders: A Retrospective Cohort Study in the United Kingdom Does Not Support a Causal Association Andrews N, et al., Pediatrics. 2004; 114(3): 584-91 ​	​Study analyzed thimerosal exposure and possible development delays in 109,863 children born in the United Kingdom from 1988-97. Exposure was defined according to the number of DTP/DT doses received by 3 and 4 months of age and also the cumulative age-specific DTP/DT exposure by 6 months.	​With the possible exception of tics, there was no evidence that thimerosal exposure via DTP/DT vaccines causes neurodevelopmental disorders.
​Immunization Safety Review: Vaccines and Autism Institute of Medicine, The National Academies Press: 2004​	​The IOM’s Committee on Immunization Safety Review was convened in the fall of 2000 to provide an independent review of increasingly prominent vaccine safety concerns. The 15 committee members with expertise in pediatrics, internal medicine, immunology, neurology, infectious diseases, epidemiology, biostatistics, public health, risk perception, decision analysis, nursing, genetics, ethics and health communications analyzed over 200 relevant studies.	​The committee rejected a causal relationship between the MMR vaccine and autism as well as a causal relationship between thimerosal-containing vaccines and autism.
​Pervasive Developmental Disorders in Montreal, Quebec, Canada: Prevalence and Links With Immunizations Fombonne, et al., Pediatrics. 2006; 118(1); e139-50	​The committee rejected a causal relationship between the MMR vaccine and autism as well as a causal relationship between thimerosal-containing vaccines and autism.	​The data rule out an association between pervasive developmental disorder and either high levels of ethyl mercury exposure comparable with those experienced in the United States in the 1990s or 1- or 2-dose measles-mumps-rubella vaccinations.
​Early Thimerosal Exposure and Neuropsychological Outcomes at 7 to 10 Years Thompson, et al., New England Journal of Medicine. 2007; 357: 1281-92   ​	​Study compared early exposure to thimerosal-containing vaccines to 42 neuropsychological outcomes in 1,047 children between the ages of 7 and 10 years. Exposure to mercury from thimerosal was determined from computerized immunization records, medical records, personal immunization records and parent interviews.	​The study does not support a causal association between early exposure to mercury from thimerosal-containing vaccines and immune globulins and deficits in neuropsychological functioning at the age of 7 to 10 years.
​Mercury Levels in Newborns and Infants After Receipt of Thimerosal-Containing Vaccines Pichichero, et al., Pediatrics. 2008; 121(2): e208-14 ​	​Study assessed blood mercury levels of 216 healthy children prior to immunization with thimerosal-containing vaccines, and 12 hours to 30 days after. The blood mercury half-life was calculated to be 3.7 days and returned to prevaccination levels by day 30.	​The blood half-life of intramuscular ethyl mercury from thimerosal in vaccines in infants is substantially shorter than that of oral methyl mercury in adults. Increased mercury levels were detected in stools after vaccination, suggesting that the gastrointestinal tract is involved in ethyl mercury elimination. Because of the differing pharmacokinetics of ethyl and methyl mercury, exposure guidelines based on oral methyl mercury in adults may not be accurate for risk assessments in children who receive thimerosal-containing vaccines.
​Continuing increases in autism reported to California’s developmental services system: mercury in retrograde Schechter and Grether, Archives of General Psychiatry. 2008;  65(1):19-24​	​Study analyzed autism client data from the California Department of Developmental Services between 1995 and 2007. Even though thimerosal was absent from scheduled childhood vaccines after 2002, cases of autism continued to climb quarter by quarter.	​The California DDS data do not show any recent decrease in autism in California despite the exclusion of more than trace levels of thimerosal from nearly all childhood vaccines. The data do not support the hypothesis that exposure to thimerosal during childhood is a primary cause of autism.
​Prenatal and Infant Exposure to Thimerosal from Vaccines and Immunoglobulins and Risk of Autism Price C, et al., Pediatrics. 2010; 126(4): 656-64​	​Researchers reviewed managed care organization records and conducted interviews with the parents of 256 children who were verified to have ASD according to a standardized personal evaluation. Children with ASD were further categorized as having autistic disorder or ASD with regression. Another 752 children without autism, matched to the ASD children by birth year, gender and managed care organization, were also studied. For none of the autism outcomes was prenatal or early life receipt of thimerosal-containing vaccines and immunoglobulins significantly greater among children with ASD than among children without ASD.	​These results add to the evidence that thimerosal-containing vaccines do not increase the risk of autism.
​Lack of Association Between Measles-Mumps-Rubella Vaccination and Autism in Children: A Case-Control Study Budzyn D, et al., The Pediatric Infectious Disease Journal. 2010; 29(5): 397-400  ​	​Researchers in Poland compared vaccination history and autism diagnosis in 96 children with autism, ages 2 to 15, as well as 192 children in a control group. For children vaccinated before a diagnosis of autism, the autism risk was lower in children who received MMR vaccine than in nonvaccinated children. A similar result was achieved for the single-antigen measles vaccine.	The study provides evidence against the association of autism with either MMR or a single measles vaccine.  ​

​Investigative Reporting 

​​​Article	​Summary
​How the case against the MMR vaccine was fixed Deer B, British Medical Journal. 2011; 342: 77-84	​​British journalist Brian Deer investigates Dr. Andrew Wakefield (the man who initially claimed a link between autism and the MMR vaccine), his practices during the study that was published on this alleged connection, and uncovers truths that lead to the revocation of Dr. Wakefield’s medical license and to the retraction of the article he published on the subject.​

Childhood vaccination has been one of modern medicines biggest success stories. In fact, vaccines for children have been so successful that we no longer see many of the diseases that used to cause severe illnesses and lasting disabilities.

Thanks to vaccines, most children will never get whooping cough, tetanus, polio or meningitis—so we rarely see how serious these diseases can be. As a result, parents may wonder if their child needs all of the recommended vaccinations.

Perhaps you’ve asked yourself this question and Googled it. These days, it’s easy to search online for answers that support a belief about risks of vaccines. But the bulk of these claims are inaccurate and unproven. A lot of this information is not just scary—it has caused parents to second-guess the facts they hear from their pediatrician and other trusted sources. And it scares people away from a vaccine that could save their child’s life.

Anti-vaccine posts are not fact-checked

Just like other rumors that go viral on social media platforms, these anti-vaccine posts are not checked for accuracy. They may not be the best or most accurate information about your baby’s vaccines. Here’s what else to keep in mind:

• Social media algorithms promote posts that are likely to appeal to a lot of people, like ones with the most clicks or followers or posts from celebrities.
• When you click on or interact with even one false piece of information, the platform will show you more and more similar kinds of content. This can lead you into a disinformation “rabbit hole” without you even realizing it.
• The posts seem authentic and convincing. That’s why they are so effective at influencing parents who are searching for answers to questions about their child’s health. These posts spread easily and get shared by tens of thousands of people who may not even know where the post came from.
• When experts post accurate content, they often get targeted by anti-vaxxers who want to drown out the facts.

Vaccine side effects & myths

For years, people have spread rumors online using a variety of angles, including rumors about vaccines and autism spectrum disorder (ASD), sudden infant death syndrome (SIDS) and developmental delays. Here are a few examples:

Vaccines & autism spectrum disorder (ASD)

In the 1990s, a paper was published by a doctor who looked at 12 kids and theorized that their autism was due to vaccines. Specifically, it looked at the measles-mumps-rubella (MMR) vaccine and a possible link to autism.

Fact: That paper turned out to be based on bad science. It was discredited and the journal retracted it. This single paper caused enough fear among parents that a lot of other studies have been done in many countries and included thousands of children. They found no causal association to link them.

Children with ASD are often diagnosed between 18 and 30 months of age—around the same time the MMR vaccine is given. This has led some people to assume that the vaccine is the cause. Increasing evidence shows that even though the symptoms of ASD may not be visible until the second year after birth or later, ASD starts before a baby is born.

Extensive evidence from the American Academy of Pediatrics (AAP), the Centers for Disease Control and Prevention, the National Academy of Medicine and researchers around the world also have concluded that there is no causal association between the MMR vaccine and autism.

Fears of a possible link between MMR vaccine and autism have led to under-vaccinated areas. Measles has been eliminated in our country since 2000, but the virus still spreads—leading to outbreaks in the United States and around the world.

Thimerosal or mercury & vaccines

A preservative (thimerosal) added to vaccines in the 1930s contains mercury. People feared that this mercury was toxic to humans. Some people thought that it could cause neurologic (nervous system) problems.

Fact: Mercury is a naturally occurring element in the earth’s crust, air, soil and water. There are two types of mercury—and they are very different.

Thimerosal contains very small amounts of one type of mercury that is added to some vaccines to prevent germs from growing. This type of mercury does not stay in the body. It is different from the other type of mercury that is found in certain kinds of fish. That type can stay in the human body and make people sick.

Even after many studies, thimerosal has never been shown to cause neurologic problems. Thimerosal has not been used in vaccines for children since 2001. Only some flu vaccines contain thimerosal. If you have any questions or concerns, ask your pediatrician.

Vaccines & SIDS

Babies get many of their first vaccines between 2 and 4 months of age. This is also the peak age for sudden infant death syndrome (SIDS ). Because of the timing, some people feel they might be related.

Fact: Scientific studies have confirmed that vaccines do not cause SIDS. In fact, vaccines may help prevent SIDS. And most importantly to help prevent SIDS, the AAP recommends a safe sleep environment for babies.

Remember

When reviewing facts about vaccines for your child, make sure you check the source. Have a high level of suspicion if you don’t recognize and trust the original source of the content.