How do I know vaccines are safe for my child?

How vaccines are monitored

The United States has one of the most advanced systems in the world to track vaccine safety. Each system below supplies different types of confidential and anonymous data that researchers analyze. Together, they help provide a full picture of vaccine safety.source: ¹¹

• Vaccine Adverse Event Reporting System (VAERS) is a system managed by CDC and FDA that helps identify possible safety issues. Anyone can submit a report to VAERS. A VAERS report does not always mean there is a safety issue. For example, let’s say a bee stings you on the arm after you got your vaccine and later in the day your arm becomes sore and swollen. Since those are side effects of both a bee sting and a vaccine, you can’t be sure what is causing the soreness and swelling. You should report it to VAERS anyway. Reporting this helps identify potential new or unusual side effects to take action if needed. Researchers will then evaluate the VAERS report to determine whether it is related to the vaccine.source: ¹²
• Vaccine Safety Datalink (VSD) is a collaboration between CDC and several health care organizations. VSD uses databases of medical records to track vaccine safety and conduct research in large populations. VSD can look at and compare data to learn whether side effects might be linked to a vaccine.
• Post-Licensure Rapid Immunization Safety Monitoring System (PRISM) uses health insurance claims to find and assess possible safety issues.
• Clinical Immunization Safety Assessment (CISA) Project provides expert consultation to health care providers with complex vaccine safety questions about a patient and conducts clinical vaccine safety research. It evaluates complex cases of possible side effects in patients.
• FDA’s Biologics Effectiveness and Safety (BEST) System uses multiple high quality data sources to evaluate the safety and effectiveness of vaccines and other biological products.
• V-safe is a CDC vaccine safety monitoring system for newer vaccines. CDC sends texts or emails to vaccinated people who volunteer to participate, asking them how they feel after getting a vaccine. This information lets others know what to expect in the days and weeks following vaccination.

Package inserts

Vaccines include a package insert that gives doctors information about how to use the vaccine. For example, the correct dosage to be used, how to give the shot properly, and vaccine storage information. The insert is a legal document, and as a result, it lists any known side effects and adverse events observed after vaccination. Package inserts generally don’t list how likely side effects are. If a single person in 1 million had an adverse reaction to a vaccine, it will be listed in the insert. Find out more about the most common side effects for different vaccines.

Research finds no link between vaccines and autism

A common misbelief is that vaccines cause autism. This claim can be traced back to a 1998 research paper. The author claimed that autism observed in eight children might be due to the MMR vaccine. Children received the vaccine around the same time their symptoms for autism were seen. The paper was later discredited. The author, a physician, had his medical license taken away for presenting dishonest science and promoting false information. Still, this paper created a lot of fear in parents. More studies were done globally among millions of children and found no link between vaccines and autism.source: ^13,source: ¹⁴

One particular meta research project (a large research project that looks at multiple studies) reviewed 10 studies with more than 1.2 million children. The authors found that vaccine ingredients like thimerosal, a preservative containing a mercury compound, were not related to children developing autism. Neither were combination vaccines like the MMR vaccine.source: ¹⁵ Another study that analyzed data collected from nearly 660,000 Danish children also found no link between vaccines and autism.source: ¹⁶ Overall, across many research studies, there was evidence that vaccines did not cause autism.source: ^13,source: ¹⁴

The reason autism is often diagnosed around the same time as vaccination is because the age when children are getting some of their first routine vaccines is also when symptoms of autism typically begin. That is when many parents first realize their child may have autism.source: ^17,source: ¹⁸

Vaccine ingredient safety

Thimerosal has been used as a preservative in multidose vaccines. It contains ethylmercury but is not harmful as an ingredient in approved vaccines. It does not build up in the body the way other types of mercury do and has a record for being very safe when used in approved medicines and vaccines.source: ^19,source: ²⁰

However, all vaccines routinely recommended for children 6 years of age and younger in the United States are available in formulations that do not contain thimerosal.source: ^21,source: ²²

Developmental disorders have increased in recent years, even though thimerosal use has dramatically decreased. Developmental disorders are caused by many factors, including pollution in the environment.source: ^14,source: ²¹ They are not caused by vaccines.source: ^14,source: ²¹ One of the reasons we are seeing an increase in developmental disorders is because we are getting better at detecting them.

Inspection and further testing for vaccine quality and safety

FDA approves vaccines for public use. Learn more about how vaccines are tested. After FDA approves a vaccine, the company that makes it is required to test every batch, which is called a “lot.”source: ⁴ The company sends information about the manufacture of the lot to FDA, including information about results of the company’s tests. These steps are taken during vaccine lot testing to ensure that vaccines are:source: ^4,source: ¹¹

• Potent: They work like they're supposed to.
• Sterile: They don't have any outside germs.
• Pure: They only contain the ingredients they are supposed to.

After vaccine lots are tested by the company, the FDA reviews the results of these tests and may also repeat some of the tests. The agency also inspects the factories where the vaccine is made. This helps ensure vaccines meet quality and safety standards.source: ²² Manufacturers can’t distribute a specific lot of a vaccine until the FDA releases it.

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