Babies & Children

Vaccines do not cause autism. Nearly a dozen studies following millions of children conducted worldwide over the last decade have failed to find a connection between autism and childhood vaccines. The original small study that claimed to find a connection was officially retracted  when it was found the lead author, Dr. Andrew Wakefield, lied about his findings. He has since lost his license to practice medicine.

Both the medical and public health communities that monitor vaccine safety have heard the claims of a vaccine-autism link, researched them extensively, and repeatedly disproved them. We encourage you to look at the evidence yourself by reading the many studies on this topic.

Parents can be confident that the medical and public health communities, including the prestigious National Academy of Medicine (NAM) (formerly known as the Institute of Medicine [IOM]), the American Academy of Pediatrics (AAP), the American Medical Association (AMA), the World Health Organization (WHO), the National Institutes of Health (NIH), the Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and many others, strongly support the safety and benefits of immunizations.

Learn more about this issue and the promising scientific research on autism at the Autism Science Foundation website.

Alison Singer is the mother of a child with autism. Watch this video below as she describes her own personal journey to becoming an autism advocate and investigating the alleged connection between autism and the MMR vaccine.

Get more of your questions about vaccines answered by visiting our Are Vaccines Safe page and choosing “vaccines and autism” in the right-hand box. 

Check out CDC’s animated video that will tell you what to expect when your children get their vaccines.

It may seem like your baby is being vaccinated too early, but the childhood schedule is carefully designed to protect children when they are most vulnerable to serious disease and when vaccines produce the strongest immune response. Experts consider the number of doses needed, appropriate timing between doses, and any precautions or contraindications for specific populations.

Immunization schedules are created based on careful review of data and evidence on how well vaccines work, disease threats to specific age groups, and vaccine safety.

Evidence-based immunization schedules are endorsed by leading U.S. medical organizations that directly represent frontline clinicians, including the American Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP). These schedules are based on rigorous review of scientific evidence on vaccine safety, effectiveness, and disease burden and are updated regularly to reflect our best available science.

Get more of your questions about vaccines answered by visiting our Questions About Vaccines section.

The child and adolescent immunization schedule is developed through careful review of data and evidence on vaccine effectiveness, disease risks for specific age groups, and vaccine safety.

Evidence-based immunization schedules are endorsed by leading U.S. medical organizations that directly represent frontline clinicians, including the American Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP). These schedules are based on rigorous review of scientific evidence on vaccine safety, effectiveness, and disease burden and are updated regularly to reflect our best available science.

This schedule is carefully designed to protect children when they are most vulnerable to serious disease and when vaccines will produce the strongest immune response. Experts consider the number of doses needed, appropriate timing between doses, and any precautions or contraindications for specific populations.

Yes. Some vaccine-preventable diseases like flu, whooping cough and measles still cause a lot of illness, hospitalizations and even death in the U.S.  And even though other vaccine-preventable diseases that we protect against are rarer in the U.S., they still occur around the world, and unvaccinated travelers can easily bring these diseases with them to the U.S., putting unvaccinated people of all ages at risk of serious illness.

Also, all vaccine-preventable diseases are not the same—some are more deadly than others; and some are more contagious than others. But whether the chance of getting sick or dying from a particular disease is 1 in 100 or 1 in 10,000, you must decide if the risk is worth taking with your children’s health. No one ever thinks that their child will be the 1 in 10,000 that will die from the vaccine-preventable disease.

Get more of your questions about vaccines answered by visiting our Questions About Vaccines section.

Vaccines are one of the most thoroughly tested medical products available in the U.S. Before a vaccine can be considered for approval by the FDA, a vaccine manufacturer must show it is safe and effective through clinical trials. Developing a new vaccine begins with exploratory stage and pre-clinical stage before advancing to three stages of clinical trials. Together, this scientific process can take over a decade and cost millions of dollars. The FDA then examines these studies and determines whether a vaccine is safe, effective, and ready to be licensed for use. The FDA only licenses vaccines that have data that shows that the vaccines’ benefits outweigh the potential risks. If there is any question about the data, or any holes in the data, the FDA will request further studies before approving the vaccine.

After a vaccine is licensed for use in the U.S., there are four systems in place that work together to help scientists monitor the safety of vaccines and identify any rare side effects that may not have been found in clinical trials. Even large clinical trials may not be big enough to find very rare side effects. For example, some side effects may only happen in 1 in 100,000 or 1 in 500,000 people. Second, vaccine trials may not include certain populations like pregnant women or people with specific medical conditions who might have different types of side effects or who might have a higher risk of side effects than the volunteers who got the vaccine during clinical trials.

Vaccine Adverse Events Reporting System (VAERS)

VAERS is a passive reporting system. That means it relies on individuals to report vaccine reactions. Anyone can report a reaction or injury, including healthcare providers, patients and patients’ representatives, such as caregivers or attorneys. The system is co-managed by the FDA and the CDC. However, it is important to note that VAERS data alone can’t be used to answer the question, “Does a certain vaccine cause a certain side effect?” This is because adverse events reported to VAERS may or may not be caused by vaccines. There are reports in VAERS of common conditions that occur just by chance after vaccination. Further investigation may find no medical link between vaccination and these conditions. Instead, the purpose of VAERS is to see if unexpected or unusual patterns emerge, which may indicate a vaccine safety issue that needs to be researched further.

The Vaccine Safety Datalink (VSD)

Established in 1990, VSD is a collaboration between the CDC’s Immunization Safety Office and eight health care organizations across the country. It conducts studies based on questions or concerns raised from the medical literature and reports to VAERS. In addition, when new vaccines are recommended or if changes are made in how a vaccine is recommended, VSD will monitor the safety of these vaccines.

The Clinical Immunization Safety Assessment Project (CISA)

CISA, which was created in 2001, is a national network of vaccine safety experts from the CDC’s Immunization Safety Office, seven medical research centers and other partners. CISA addresses vaccine safety issues, conducts high quality clinical research and assesses complex clinical adverse events following vaccination. CISA also helps to connect clinicians with experts who can help consult on vaccine safety questions related to individual patients.

The Post-Licensure Rapid Immunization Safety Monitoring System (PRISM)

PRISM is a partnership between the FDA’s Center for Biologics Evaluation and Research and leading health insurance companies. It actively monitors and analyzes data from a representative subset of the general population. PRISM links data from health plans with data from state and city immunization information systems (IIS). PRISM has access to information for over 190 million people allowing it to identify and analyze rare health outcomes that would otherwise be difficult to assess.

Download VYF’s handout – How Do We Know Vaccines are Safe?

Get more of your questions about vaccines answered by visiting our Questions About Vaccines section.

You may have heard that vaccines contain many ingredients that sound as though they don’t belong in a medical product. The truth is that a very small group of very vocal, but misinformed, individuals have made false accusations regarding the safety of vaccines and their ingredients. In most instances, these allegations are incorrect. In other cases, the claims are misinformed or taken out of context.

The main ingredients in vaccines are antigens, which are small amounts of the bacteria or virus against which the person is being vaccinated. Antigens are the parts of the vaccine that encourage your immune system to create antibodies to fight against future infections. To make sure that the vaccines cannot cause the disease you are trying to protect against, the antigens are altered or weakened. Learn more about how vaccines are made and how they work.

Like many of the foods we eat and beverages we drink, vaccines also contain a small amount of additional ingredients, and each has a specific, necessary function. These ingredients may be added to the vaccine to make it more effective, sterile, and/or safe. These additional ingredients have been studied and are safe for humans in the amount used.

The amount of these additional ingredients in vaccines is much less than children encounter in their environment, food, and water. As the saying goes, “the dose makes the poison.” In other words, any chemical—even water or oxygen—can be toxic or even deadly in large enough quantities.

Sometimes a child may be sensitive to a component of a vaccine, and an allergic reaction may result. For this reason, you should discuss any allergies your child may have with your healthcare provider. Below are the ingredients that may be found in certain vaccines and their purpose:

Preservatives

When an individual vaccine dose is drawn from a multi-dose vaccine vial with a fresh needle, it is possible for bacteria or fungi to get into the vial, which could be very dangerous. To prevent this contamination, a preservative is added to the vaccine.

Thimerosal (a preservative)

Thimerosal is an ethylmercury-based preservative used in multi-dose vials of vaccines to prevent contamination. If someone were to receive a vaccine contaminated with bacteria, it could be deadly.

Ethylmercury is very different than methylmercury, which is found naturally in the environment, and what people commonly think of when they hear the word “mercury.” The low levels of ethylmercury in vaccines are metabolized differently and are cleared from the blood more quickly than methylmercury. A buildup of methylmercury in the body usually results from eating certain types of fish or other foods, and high levels can harm the nervous system.

Although there is no evidence that thimerosal in vaccines was dangerous, in 1999, it was removed from vaccines in the U.S. in an effort to reduce overall mercury exposure among infants. To keep vaccines safe from contamination without the use of thimerosal or other preservatives, they were either reformulated or packaged in single-dose vials. Now, the only vaccines in the U.S. that use thimerosal as a preservative are flu vaccines in multi-dose vials. (Thimerosal-free, single-dose vials of flu vaccine are also available in the U.S.) Thimerosal in multi-dose vials is necessary because each time an individual dose is drawn from a multi-dose vial with a new needle and syringe, there is a risk of contamination. There is no evidence that the small amounts of thimerosal in flu vaccines cause harm, except for minor reactions like redness and swelling at the injection site.

To learn more about the thimerosal content in FDA-approved seasonal flu vaccines, visit the Thimerosal and Vaccines page on the Food and Drug Administration (FDA) website. MMR (measles, mumps, and rubella), chickenpox (varicella), inactivated polio (IPV), and pneumococcal conjugate vaccines (PCV) NEVER contained thimerosal as a preservative.

No credible scientific studies have found an association between thimerosal in vaccines and autism. The studies used different methods to find out if there was any connection between thimerosal and autism. Some examined rates of autism in a state or a country, comparing autism rates before and after thimerosal was removed as a preservative from vaccines. It is important to note that in the U.S. and other countries, the number of children diagnosed with autism has not gone down since thimerosal was removed from childhood vaccines. To read the studies yourself, visit our Vaccine Research page.

Formaldehyde

Formaldehyde is a colorless gas that is a byproduct of metabolism, so it is already present in the human body. People also encounter formaldehyde every day in the environment. It is used in making building materials and many household products, and formaldehyde also gets into the air through car tailpipe emissions.

Formaldehyde is used to inactivate bacterial products for toxoid vaccines (DTaP and Tdap), and to kill unwanted viruses and bacteria that might contaminate the vaccine during the manufacturing process. Most formaldehyde is removed from the vaccine before it is packaged. In trace amounts, formaldehyde is not dangerous. In fact, there is more formaldehyde in a pear than in any one vaccine.

Aluminum

For over 75 years, aluminum gels or salts have been added as adjuvants to some vaccines to enhance their ability to stimulate the body’s immune system. Without an adjuvant, healthcare providers would need to give more shots in a vaccine series or face lower immunity from the vaccine, and therefore less protection from the disease. Aluminum is also commonly found in food, water, infant formula, and even breast milk.

Adjuvants

Adjuvants, such as aluminum, are added to certain vaccines to help trigger a better immune response. Without the adjuvant, we would need to administer more shots in the vaccine series or face lower immunity and therefore less protection against the disease. Studies have shown there is no connection between adjuvants and the development of autoimmune diseases.

Residual Antibiotics

Antibiotics are added to some vaccines to prevent the growth of bacteria during the manufacturing process and storage of the vaccine. No vaccine produced in the United States contains penicillin.

Egg Protein

Some vaccines, like MMR and some flu vaccines, are prepared in eggs, which means that some egg proteins are present in the final vaccine product. The egg proteins help manufacturers to grow enough of the virus or bacteria needed to make the vaccine. Based on scientific evidence, the American Academy of Pediatrics (AAP) states that the MMR vaccine can be safely given to all patients with egg allergies, including patients with a history of severe, generalized anaphylactic reactions to eggs.  AAP also states that “children with egg allergy can receive influenza vaccine with no additional precautions than those considered for any vaccine.”  Additionally, the American Academy of Allergy, Asthma & Immunology (AAAAI) states “Studies show that flu vaccines can be safely administered to egg allergic individuals.” If you or your child are allergic to eggs, make sure to tell your doctor or healthcare provider before getting vaccinated.

Gelatin

Some vaccines contain gelatin to protect them against freeze-drying or heat during the transportation and storage process. People with severe allergies to gelatin should talk to their doctor or healthcare provider before getting vaccinated.

Antifreeze

You may have heard that vaccines contain products such as antifreeze. This is not true. Antifreeze typically contains ethylene glycol, an unsafe and highly toxic (poisonous) component, or propylene glycol, a safer and less toxic option to ethylene glycol. Neither of these members of the glycol family of compounds is used in vaccines. In vaccines, polyethylene glycol is used to inactivate the virus in some influenza vaccines and to purify other vaccines. Polyethylene glycol is FDA-approved and considered non-toxic for medical and other uses.* It is used in a variety of products, including skin cream, toothpaste, lubricating eye drops, laxatives, and as an anti-foaming agent in food. It is also used as an irrigating solution in surgical procedures.

* Victor O. Sheftel (2000). Indirect Food Additives and Polymers: Migration and Toxicology. CRC Press, 1114-1116.

Read more about ingredients in vaccines and why they are in there.

Get more of your questions about vaccines answered by visiting our Questions About Vaccines section.

Even breastfed babies need to be protected with vaccines at the recommended ages. While breast milk provides important protection against some infections like colds, ear infections, and diarrhea, it will not protect him or her against all diseases.

Your baby needs the long-term protection that can only come from making sure he or she receives all his vaccines according to the recommended immunization schedule, before he or she is exposed to diseases.