Vaccination Safety

Vaccines provide our best defense against certain diseases, but vaccines may not be 100 percent safe or effective. Getting vaccinated, like taking any medication, could lead to side effects.

However, before the Food and Drug Administration (FDA) approves a vaccine, that vaccine must be tested extensively (typically in thousands to tens of thousands of people) to ensure it is safe.

In fact, vaccines are tested much more rigorously than most medications. That is because vaccines are usually given to healthy people to prevent illness, unlike many medicines, which are given to sick people to treat a preexisting condition. The burden to “do no harm” is therefore greater with vaccines.

In addition, the safety of approved vaccines is continuously monitored by the manufacturers, the Centers for Disease Control (CDC) and the FDA. The FDA requires each manufacturer to test samples from every lot for safety, potency and purity, and the FDA also carries out its own tests.

The CDC and the FDA jointly manage the Vaccine Adverse Event Reporting System (VAERS), a voluntary reporting system used by patients, manufacturers, public health officials, and healthcare professionals to report potential adverse effects from vaccinations. Using reports from VAERS, CDC scientists can look for patterns that suggest a side effect is actually caused by the vaccine.

The latest research supports that vaccination’s benefits outweigh its risks. Use the resources on this page to learn more about what the scientific evidence says about vaccine safety.



Vaccination for Adults

Vaccination for School-Age Children

H1N1 Information

Vaccine Home