All vaccines, including the Pfizer and Moderna SARS CoV2 vaccines that are being deployed right now are continually monitored for safety using the Vaccine Adverse Event Reporting System (VAERS) monitoring system. VAERS is managed jointly by the CDC and FDA and monitors for problems or “adverse events” that happen after vaccination.

In addition to the tried and true VAERS system, there are several additional safety systems in place for the SARS CoV2 vaccines.  Here’s a summary of the various safety monitoring systems that are being used.


Data from the system gives the CDC and FDA important information that might signal a problem. If it looks as though a vaccine might be associated with an adverse event, the FDA and CDC investigate further.  Healthcare providers, patients and caregivers can report into the VAERS system. The CDC and FDA encourage anybody who experiences any problems after vaccination to report to VAERS. Healthcare providers are required by law to report certain problems.

Vaccine Safety Datalink

Scientists use the VAERS data and the CDC’s Vaccine Safety Datalink (VSD) to do studies that investigate vaccine safety.  VSD is a network of eight managed care organizations across the United States. Scientific teams use VSD in two ways.

First, scientists can look back in medical records to see if a particular adverse event is more common among people who have received a particular vaccine.

Second, they use Rapid Cycle Analysis to continuously look at information coming into VSD to see if the rate of certain health conditions is higher among vaccinated people. When potential adverse events or trends are identified a more in-depth review is conducted.


The CDC has also implemented a new system called V-safe or After Vaccination Health Checker which is in place specifically for the SARS CoV-2 vaccines. V-safe is a smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after you receive a COVID-19 vaccination.

Through v-safe, you can quickly tell CDC if you have any side effects after getting the COVID-19 vaccine. Depending on your answers, someone from CDC may call to check on you and get more information. V-safe also reminds you to get your second COVID-19 vaccine dose if you need one. Here is the V-Safe After Vaccination Health Checker website.

In-depth Review for Sensitive Subpopulations

Additional COVID specific safety investigations are being planned for sensitive sub-populations. For example, there are a number on initiatives underway including:

1) the FDA and CMS are collaborating on an in-depth review of vaccinated seniors through Medicare;

2) the VA is conducting an in-depth review of veterans that get vaccinated;

3) the FDA is reviewing in depth among certain insured groups through the BEST and PRISM sites;

4) IHS will have a specific review for their members; 5) the Department of Defense will be specifically looking into adverse events among active duty personnel and; and 6) Genesis Healthcare will specifically be studying long-term care residents.

You can review the overarching safety monitoring in this COVID-19 vaccine post-authorization safety monitoring update.

Vaccine Manufacturing Safety

In addition, FDA regularly inspects vaccine manufacturing facilities to make sure they are following strict regulations. Vaccines are manufactured in batches called lots, and vaccine manufacturers must test all lots of a vaccine to make sure they are safe, pure, and potent. Vaccine lots cannot be distributed until released by FDA.