Common questions about VAERS data, our methodology, and how to interpret vaccine adverse event reports.
The Vaccine Adverse Event Reporting System (VAERS) is a national early warning system co-managed by the CDC and FDA to detect possible safety problems in U.S.-licensed vaccines. It accepts reports of adverse events that occur after vaccination from healthcare providers, manufacturers, and the public.
No. VAERS reports describe events that happened after vaccination, but this temporal association does not prove causation. Many reported events may be coincidental, occurring at the same rate they would in an unvaccinated population. Reports may also contain incomplete or inaccurate information.
COVID-19 vaccines were administered to hundreds of millions of people in a short timeframe, during a period of intense public scrutiny and media attention. This led to dramatically higher reporting rates compared to other vaccines — a well-documented phenomenon called "stimulated reporting." More reports does not necessarily mean more risk.
Anyone can file a VAERS report — healthcare providers, vaccine manufacturers, patients, and family members. Healthcare providers are legally required to report certain serious adverse events. This openness is both a strength (broad signal detection) and a limitation (unverified reports).
We process the raw VAERS data files published quarterly by the CDC/FDA and present them in an accessible, searchable format. We add context, disclaimers, and analysis to help people understand what the numbers mean — and what they don't mean.
VAERS data is published quarterly by the CDC/FDA. We update our database shortly after each new data release. The current dataset includes reports through 2026.
Report volume is primarily driven by how many doses of a vaccine have been administered, public awareness, media attention, and mandatory reporting requirements. Higher report counts do not indicate higher risk. See our analysis on the denominator problem for more context.
VAERS provides report counts (numerators) but not the number of vaccine doses administered (denominators). Without knowing how many people received each vaccine, raw report counts cannot be used to calculate or compare risk rates. This is the single most important limitation of VAERS data.
Neither. We are a data transparency project. We present VAERS data as-is, with appropriate context and disclaimers. We don't make recommendations about vaccination. Our goal is informed transparency — helping people understand the data so they can have better conversations with their healthcare providers.
This website is for educational and informational purposes only. It is not medical advice. Always consult qualified healthcare professionals for medical decisions, including vaccination decisions.
We define serious outcomes as reports that mention death or hospitalization. The serious outcome rate is (deaths + hospitalizations) / total reports × 100. This is a rough measure of report severity, not a measure of vaccine risk.
VaccineWatch is part of TheDataProject.ai, a collection of data transparency tools. Our sister sites include OpenMedicaid, OpenFeds, OpenSpending, OpenMedicare, and OpenLobby — all focused on making government data accessible and understandable.
A side effect is a health problem that has been shown to be caused by a vaccine. An adverse event is any health problem that happens after vaccination, whether or not the vaccine caused it. VAERS collects adverse events, so most reports are not confirmed side effects — they are events that occurred in the time window after a vaccine was given.
You can browse by vaccine, by symptom, by U.S. state, or by manufacturer, and compare vaccines side by side. Start from the vaccines directory to see reports and outcomes for each vaccine, or use the symptoms directory to find which vaccines are most associated with a given symptom. Our search tool lets you find specific vaccines and symptoms quickly.
These come directly from checkbox fields on the VAERS report form. "Died" means the report noted a death, "hospitalized" means an inpatient stay, "ER" means an emergency room or doctor visit, and "disabled" means a permanent disability was reported. A single report can carry more than one flag, and none of these flags confirm that the vaccine caused the outcome.
Yes. All of our figures come from the official public-use VAERS datasets published by the CDC and FDA at vaers.hhs.gov. You can download the same raw CSV files, and our methodology page documents exactly how we process them, so anyone can reproduce our numbers.
No. Death reports in VAERS are not confirmed vaccine-caused deaths. When hundreds of millions of people are vaccinated, some will die of unrelated causes in the days afterward purely by coincidence, and those deaths may be reported to VAERS. Determining whether a vaccine actually increases the risk of death requires controlled studies that compare vaccinated and unvaccinated populations, not raw report counts.
A safety signal is a pattern in the data that suggests a possible link between a vaccine and an adverse event and warrants a closer look. VAERS is designed to detect these signals. Once a signal appears, it is investigated with more rigorous systems such as the Vaccine Safety Datalink (VSD) and the Clinical Immunization Safety Assessment (CISA) project, which can actually test for causation.
VAERS removes personally identifying information before reports are made public. The public-use files we work with do not contain names or contact details. VaccineWatch only uses these already-de-identified public datasets and does not collect or store any individual report submissions.
Explore symptom onset timing patterns after vaccination.
Compare 2-3 vaccines side by side with charts and stats.
See reporting patterns across all 50 states and territories.
VAERS is one component of a larger vaccine safety monitoring ecosystem. Understanding how these systems work together helps put VAERS data in perspective:
When VAERS detects a potential safety signal, it is investigated using these more rigorous systems. The myocarditis signal after mRNA COVID-19 vaccines is a perfect example: VAERS detected the pattern, VSD confirmed the elevated risk, and clinical studies characterized the condition and its outcomes.
VAERS is one component of a larger vaccine safety monitoring ecosystem. Understanding how these systems work together helps put VAERS data in perspective:
When VAERS detects a potential safety signal, it is investigated using these more rigorous systems. The myocarditis signal after mRNA COVID-19 vaccines is a perfect example: VAERS detected the pattern, VSD confirmed the elevated risk, and clinical studies characterized the condition and its outcomes.
Learn more about our data sources and methodology.