Vaccine Safety Datalink

Overview

The Vaccine Safety Datalink (VSD) is a collaborative project between CDC and healthcare organizations across the United States. Established in 1990, the VSD members monitor the safety of vaccines and conduct studies about rare and serious adverse events following immunization.

VSD is made up of 13 member sites:

  • 11 full participant sites provide electronic health record (EHR) data shared under a common data model with a standard data dictionary.
  • Two sites provide subject matter expertise.

Centers for Disease Control and Prevention

Immunization Safety Office

Key Partners & Accomplishments

Objectives

  • Conduct research on important vaccine safety questions in large populations.
  • Conduct vaccine safety studies from questions or concerns in the medical literature or from other vaccine safety systems such as the Vaccine Adverse Event Reporting System (VAERS).
  • Monitor possible rare and serious adverse events when the FDA licenses new vaccines or when the CDC Advisory Committee on Immunization Practices (ACIP) makes new vaccine recommendations. ACIP makes vaccine safety recommendations for the United States.
  • Provide timely information to ACIP.

VSD data

To accomplish these objectives, VSD reviews:

  • EHR data from member sites that are healthcare organizations, including

    • The type of vaccine given

    • The date of vaccination

    • Other vaccinations given on the same day

  • Medical illnesses diagnosed during any visit to the healthcare facility

Evaluating adverse events in near-real time

Researchers analyze EHR data from member sites every week to determine if the rates of specific adverse events of special interest (AESI) following a specific vaccine are higher than those in a comparison group.

  • If the rate is higher in the vaccinated group beyond a certain limit, the vaccine may be associated with an adverse event. If this occurs, CDC conducts follow-up analyses.
  • VSD publishes important safety information about many vaccines — including COVID-19, HPV, influenza and more — using RCA. 12345678910111213

Evaluating safety of vaccines in pregnancy

  • VSD has developed algorithms that do the following:
    • Identify women who are pregnant
    • Determine the start and end dates of their pregnancies
    • Link medical records for pregnant women and their infants

This helps ensure the desired study participants meet the criteria for inclusion. With the appropriate study population defined, VSD can then conduct vaccine safety studies on this population and their children.