How to Search VAERS Data

VaccineWatch vs CDC WONDER

The official way to search VAERS is through CDC WONDER. It's powerful but has a steep learning curve. Here's how VaccineWatch compares:

Bottom line: Use VaccineWatch for browsing, exploring, and understanding VAERS data. Use CDC WONDER for specific custom queries that require full database access.

Tips for Interpreting What You Find

When you search VAERS data, keep these principles in mind to avoid common misinterpretations:

• Reports ≠ confirmed adverse events. A report means something happened after vaccination, not that the vaccine caused it.
• More reports often means more doses given. COVID-19 vaccines have the most reports because they were given to the most people. See our denominator problem analysis.
• Sort by severity rate, not just raw count. A symptom with 100,000 reports and 0.5% severity is less clinically significant than one with 500 reports and 50% severity.
• Look at timing patterns. Reactions within 0–3 days of vaccination are more likely to be vaccine-related than events occurring weeks later.
• Compare with background rates. If 3–4% of all births involve defects regardless of vaccination, birth defect reports after vaccination are expected.
• Check multiple sources. VAERS is one tool. Confirmed vaccine safety information comes from clinical trials, VSD studies, and expert review.