data tracking

How We Track the Frequency of Adverse Reactions to Vaccines: The Vaccine Safety Datalink

Braden A. Blumenstiel, JD April 23, 2024

Although vaccines serve an important role in maintaining the public’s health, some people have negative reactions to them. When someone experiences negative side effects of a vaccine, what they have experienced is known as an “Adverse Reaction”. The level of severity of adverse reactions to vaccines varies widely from very minor and temporary to permanent and completely debilitating…or even death.

Due to the seriousness of adverse reactions to vaccines, it is important to have the ability to determine how frequently people experience them. One way the frequency of adverse reactions to vaccines is tracked in America is through the Vaccine Safety Datalink (VSD).

The federal government created the Vaccine Safety Datalink (VSD) in 1990 to monitor the safety of vaccines and conduct studies about potential adverse events or reactions following immunization. The VSD is a collaborative project between the Centers for Disease Control and Prevention (CDC) Immunization Safety Office, integrated healthcare organizations, and networks across the United States.

Information obtained by the VSD is used to make vaccine safety recommendations throughout the country.


What Organizations Are a Part of The Vaccine Safety Datalink?

As of the writing of this article, there are 13 VSD sites that provide clinical, methodological, and data expertise and information to the VSD. They are:

  • Kaiser Permanente Washington, Seattle, Washington

  • Harvard Pilgrim Health Care, Boston, Massachusetts

  • HealthPartners Institute, Bloomington, Minnesota

  • Kaiser Permanente Northwest, Portland, Oregon

  • Kaiser Permanente Northern California, Oakland, California

  • Kaiser Permanente Colorado, Denver, Colorado

  • Denver Health Medical Center, Denver, Colorado

  • Marshfield Clinic Research Institute, Marshfield, Wisconsin

  • Kaiser Permanente Southern California, Los Angeles, California

  • Kaiser Permanente Mid-Atlantic States (Rockville, MD)

  • Acumen (Burlingame, CA)

  • Indiana University (Indianapolis, IN)

  • OCHIN (Portland, OR)


How does VSD Assess the Safety of Vaccines?

The VSD uses electronic health data from the organizations above to monitor and assess the safety of vaccines. They collect information about:

  • The kind of vaccine given to each patient,

  • The date of vaccination,

  • Other vaccinations given on the same day, and

  • What types of adverse reactions were experienced as a result of the vaccine(s).  

The VSD also uses information about illnesses that have been diagnosed at doctors’ offices, urgent care visits, emergency department visits, and hospital stays to help monitor the safety of vaccines.

The program conducts vaccine safety studies based on questions or concerns raised from the Vaccine Adverse Event Reporting System (VAERS). When there are new vaccines that have been recommended for use in the United States, or if there are changes in how a vaccine is recommended, the VSD will monitor the safety of these vaccines.

Data from the VSD has been used to address a number of vaccine safety concerns over the past 30 plus years. Examples include a study examining the risk of anaphylaxis after vaccine administration as well as studies evaluating the safety of vaccines given to pregnant women.


How to Access Vaccine Safety Data

Depending on the request, interested individuals may be able to access VSD data and data from VSD publications through public use datasets, the VSD data sharing program, and collaboration with current VSD investigators.


I've Suffered an Adverse Reaction to a Vaccine, What Do I Do?

If you have experienced an adverse reaction after a vaccination, you may be entitled to financial compensation under the National Vaccine Injury Compensation Program (NVICP).

Some adverse reactions occur frequently enough after vaccination that the National Vaccine Court will presume that the symptoms are a direct result of vaccination. These types of injuries are processed relatively quickly and compensation is often provided.

At DuPont and Blumenstiel, we have a team of attorneys, nurses, and experienced staff members ready to fight for you and your Vaccine Act claim. For additional information regarding your rights, please call our office at 614-389-9711.

To learn more about the National Vaccine Injury Compensation Program, download our free guide here.

About the Author, Braden Blumenstiel, Vaccine Injury Attorney

Braden A. BlumenstielThe law gives Braden a pragmatic way to solve problems using his background in clinical psychology. He is a talented presenter in the courtroom, as he understands how to effectively question witnesses and relay information. He specializes in vaccine injury, personal injury, probate litigation, and business law, and has been recognized for his work by SuperLawyers.


U.S. Northern District, U.S. Southern District, Ohio


Juris Doctorate - Moritz College of Law at the Ohio State University, 2004