Vaccine Adverse Event Reporting System (VAERS)
Important Things To Know About VAERS
- VAERS is an early warning system used to monitor adverse events that happen after vaccination. VAERS is the frontline system of a comprehensive vaccine safety monitoring program in the United States. It is one of several systemspdf icon CDC and the U.S. Food and Drug Administration (FDA) use to help ensure vaccines used in the United States, including COVID-19 vaccines, are closely monitored for safety.
- VAERS gives vaccine safety experts valuable information so they can assess possible vaccine safety concerns, including the new COVID-19 vaccines. It is especially useful for detecting unusual or unexpected patterns of health problems (also called “adverse events”) that might indicate a possible safety problem with a vaccine.
- If a health problem is reported to VAERS, that doesn’t mean that the vaccine caused the problem. It warns vaccine safety experts of potential problems that they may need to assess, and it alerts them to take further action, as needed.
- Hundreds of millions of people in the United States have received at least one dose of COVID-19 vaccine. The majority of reports to VAERS after COVID-19 vaccination have been non-serious adverse events. CDC provides timely updates on selected adverse events reported after COVID-19 vaccination.
How Reports Come into VAERS
VAERS collects reports of possible adverse events that happen after vaccination. Anyone can submit a report to VAERSexternal icon, including patients, parents or caregivers, healthcare providers, and vaccine manufacturers.
Under Emergency Use Authorization, FDA requires healthcare professionals to report to VAERS certain adverse eventsexternal icon that occur after COVID-19 vaccination. CDC also encourages reporting of any medically important adverse event even if it isn’t clear if the vaccine caused the health problem. This helps public health officials monitor and follow-up on possible safety problems. Learn more about selected adverse events reported to VAERS.
How VAERS Reports Are Reviewed
Vaccine safety experts review all reports of serious adverse events submitted to VAERS. A serious adverse event after vaccination is something that causes
- Permanent disability
- Hospitalization or an extended hospital stay (if vaccinated while in the hospital)
- Life-threatening illness
- Birth defects (congenital anomalies)
When VAERS staff members follow-up on a report of a serious adverse event, they ask for the patient’s medical records related to the event to learn more about what happened.
VAERS reports are available to the public, but to protect privacy and confidentiality they do not include information that could identify the person.
VAERS reports alone generally cannot be used to determine if a vaccine caused or contributed to an adverse event or illness. Some reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. VAERS reports often lack contextual information, such as total vaccinations given or information on unvaccinated groups for comparison. Most reports to VAERS are voluntary, which means they may be subject to biases. Data from VAERS reports should always be interpreted with these limitations in mind.
Learn more about how VAERS helps to monitor vaccine safety.