Vaccine Adverse Event Reporting

Immunization Section, Vaccine Safety

Vaccines are a safe and effective way to limit serious illnesses, hospitalizations, and deaths from vaccine-preventable diseases. In fact, vaccines have been so successful at combating some infectious diseases, many of us don’t know much about the diseases vaccines prevent, because we’ve never known someone who has had them. To ensure the continued success of vaccines in the United States, public health professionals are committed to making sure that vaccines are safe.

Most people do not have serious side effects from vaccines. Most side effects from vaccines are mild and go away on their own. Many common side effects after vaccination, like muscle aches or mild fever, are signs that our bodies are building a healthy immune response to protect us from disease.

An “adverse event” is any health problem that happens after a person gets a vaccine. Adverse events may be caused by the vaccine, or they may be from an unrelated cause. Sometimes it is difficult to know whether a vaccine has caused an adverse event, and that’s why safety monitoring is important. Monitoring allows scientists to look for trends, and it also helps develop guidelines about which people should not receive certain vaccines because they may be more likely to experience an adverse event. These guidelines are called precautions or contraindications. Whether you are a healthcare provider, parent, or someone who has been vaccinated, you can be a part of vaccine safety monitoring through the Vaccine Adverse Event Reporting System (VAERS).

Ask your doctor about any concerns you may have regarding vaccines. There are also many reliable online resources to answer your questions and help you make an informed, confident choice regarding vaccinations for yourself and your family. 

Vaccine Safety Assurance

Vaccines are held to a very high safety standard. They undergo careful safety testing before they are licensed, and they are monitored for safety throughout all stages of use.

CDC Infographic: The Vaccine Life Cycle

Adverse Event Prevention

The risk of vaccine adverse events can be reduced by screening for precautions and contraindications prior to administration of any vaccine. The Advisory Committee on Immunization Practices (ACIP) provides General Best Practice Guidelines for Immunization, which address contraindication and precautions. They also provide information on some common conditions that may be misunderstood as contraindications, and in which vaccination is generally safe. 


Frequently Asked Questions