Vaccines: A Safe Choice
Are vaccines tested and monitored for safety?
Yes. Before vaccines are licensed, the FDA requires they be extensively
tested to ensure safety. This process can take 10 years or longer. Once a
vaccine is in use, the CDC and FDA monitor its side effects through the Vaccine
Adverse Event Reporting System (VAERS). Any hint of a problem with a vaccine
prompts further investigations by the CDC and FDA. If researchers find a
vaccine may be causing a side effect, the CDC and FDA will initiate actions
appropriate to the nature of the problem. This may include the changing of
vaccine labels or packaging, distributing safety alerts, inspecting
manufacturers' facilities and records, withdrawing recommendations for the use
of the vaccine, or revoking the vaccine's license. For more information about
VAERS, visit www.vaers.org or call the toll-free VAERS information line at
For a quick reference sheet on key vaccine safety elements, an explanation
of VAERS, and "what happens when rare, adverse events are detected?",
consult the Surveillance and Vaccine Safety fact sheet.
Who should not be vaccinated?
Some people should not get certain vaccines or should wait to get them. For
instance, children with compromised immune systems, as occurs with cancer
patients, often need to wait to be vaccinated. Similarly, if a person has had a
severe allergic reaction to a vaccine, she or he should not receive another
dose. However, a person with a mild, common illness, such as a cold with a
low-grade fever, does not have to wait to be vaccinated. Ask your health care
provider for more information.
What should be done if someone has a reaction to a vaccine?
- Call a doctor. If the person is having a severe reaction get him or her to
a doctor right away.
- After any reaction, tell your doctor what happened, the date and time it
happened, and when the vaccination was given.
- Ask your doctor, nurse, or health department to file a VAERS form, or call
VAERS yourself at 1-800-822-7967.
Tell me more.
Please call our CDC National Immunization Information Hot Line at any time.
Also, explore other areas of this immunization website (http://www.cdc.gov/nip) for the
most current and reliable information on vaccine safety.
CDC National Immunization Information Hot Line
Visit these web sites for vaccine safety information and general information
Immunization Action Coalition (IAC) at http://www.immunize.org
National Network for Immunization Information (NNii) at http://www.immunizationinfo.org
Children's Hospital of Philadelphia Vaccine Education Center at http://www.vaccine.chop.edu/index/shtml