Important: VAERS reports alone cannot determine if a vaccine caused an adverse event. Reports may contain incomplete, inaccurate, or unverified information. Correlation does not equal causation.
VAERS reporting varies dramatically by state. Population size is the dominant factor, but per-capita analysis reveals interesting patterns in reporting culture.
The states with the most VAERS reports are, unsurprisingly, the most populous. California leads with 175,812 reports, followed by other large states. This is expected — more people means more vaccinations, which means more temporal associations with adverse events.
When adjusting for population, the picture changes significantly. Alaska leads with 879 reports per 100,000 residents. Per-capita rates can be influenced by healthcare provider awareness of VAERS, state-level reporting mandates, and demographic factors like age distribution.
A significant 16% of VAERS reports (307,638) have unknown or missing state information. This represents a major limitation in geographic analysis. Reports from healthcare providers may not always include patient state, and online submissions may omit location data.
As VAERS reporting normalizes following the COVID-19 pandemic surge, the data landscape for geographic variation in reporting is shifting. Annual VAERS reports in 2025-2026 have returned to the 35,000-45,000 range typical of the pre-pandemic era (2015-2019), making year-over-year comparisons more meaningful again.
The HHS administration has signaled increased focus on vaccine safety data analysis, including the development of AI-powered tools for pattern detection in VAERS reports. While these tools are still under development, they represent a potential evolution in how adverse event data is analyzed and interpreted.
New vaccines entering the market — including RSV vaccines for older adults and pregnant women, updated COVID-19 formulations, and potential H5N1 avian flu vaccines — continue to add new data streams to VAERS. Each new vaccine type provides additional context for understanding geographic variation in reporting across the full spectrum of vaccine safety surveillance.
This analysis is based entirely on VAERS passive surveillance data, which carries important limitations that must be understood:
For these reasons, VAERS data is best used for signal detection — identifying potential safety concerns that warrant further investigation — rather than for definitive risk assessment. When VAERS surfaces a potential signal, it is investigated using more rigorous systems like the Vaccine Safety Datalink (VSD) and controlled epidemiological studies.
All data on VaccineWatch comes from the official VAERS public-use datasets published by the CDC and FDA. Our current dataset covers reports from 1990 through early 2026. We process the raw data without filtering or editorializing — every metric is a transparent aggregation of official government data.
As VAERS reporting normalizes following the COVID-19 pandemic surge, the data landscape for geographic variation in reporting is shifting. Annual VAERS reports in 2025-2026 have returned to the 35,000-45,000 range typical of the pre-pandemic era (2015-2019), making year-over-year comparisons more meaningful again.
The HHS administration has signaled increased focus on vaccine safety data analysis, including the development of AI-powered tools for pattern detection in VAERS reports. While these tools are still under development, they represent a potential evolution in how adverse event data is analyzed and interpreted.
New vaccines entering the market — including RSV vaccines for older adults and pregnant women, updated COVID-19 formulations, and potential H5N1 avian flu vaccines — continue to add new data streams to VAERS. Each new vaccine type provides additional context for understanding geographic variation in reporting across the full spectrum of vaccine safety surveillance.
This analysis is based entirely on VAERS passive surveillance data, which carries important limitations that must be understood:
For these reasons, VAERS data is best used for signal detection — identifying potential safety concerns that warrant further investigation — rather than for definitive risk assessment. When VAERS surfaces a potential signal, it is investigated using more rigorous systems like the Vaccine Safety Datalink (VSD) and controlled epidemiological studies.
All data on VaccineWatch comes from the official VAERS public-use datasets published by the CDC and FDA. Our current dataset covers reports from 1990 through early 2026. We process the raw data without filtering or editorializing — every metric is a transparent aggregation of official government data.