Vaccine Adverse Event Reports from U.S. Surveillance System

The Vaccine Adverse Event Reporting System (VAERS) online database provides counts and percentages of adverse event case reports after vaccination. It is a post-marketing safety surveillance program collecting information on possible side effects from US licensed vaccines, managed by the CDC and FDA. Data includes breakdowns by symptom, vaccine product, manufacturer, onset interval, outcome, demographic details, and geography.

Use Cases

• Analyze symptom frequency and severity by vaccine product and manufacturer to monitor post-market safety signals.
• Model the relationship between onset interval and reported outcome categories to identify temporal risk patterns.
• Examine geographic variation in adverse event reporting rates by state and territory to assess surveillance coverage.
• Investigate demographic patterns in adverse events by analyzing data segmented by age and sex.

Strengths

• Data is sourced from a national, government-run post-marketing safety surveillance program for U.S. licensed vaccines.
• Reports include detailed breakdowns across multiple dimensions such as symptom, vaccine product, manufacturer, onset interval, and outcome.
• The dataset was last updated in June 2025, indicating recent maintenance.

Limitations

• The dataset contains aggregated counts and percentages; individual case-level data is not available for detailed patient-level analysis.
• As a passive reporting system, VAERS data is subject to under-reporting, reporting biases, and cannot establish causal relationships between vaccines and adverse events.
• The specific number of rows (total reports) and columns (data fields) is not provided in the input, limiting assessment of scale and granularity.

Provenance

Source

U.S. Department of Health & Human Services, Public Health Service, Food and Drug Administration (FDA) / Centers for Disease Control (CDC), Vaccine Adverse Event Reporting System (VAERS).

Collection Method

Data is collected through a cooperative post-marketing safety surveillance program where healthcare providers, manufacturers, and the public can voluntarily report adverse events following immunization.

Freshness

Last updated on 2025-06-20.

Geography

United States, including states and territories.