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.
A small number of companies dominate VAERS reporting. The top 5 manufacturers account for 77% of all reports — but this tells us more about market share than safety.
VAERS tracks reports from 47 manufacturers, but the market is heavily concentrated. The top manufacturer, Pfizer / BioNTech, alone accounts for 559,257 reports (21.2%).
This concentration is almost entirely driven by COVID-19 vaccines. Pfizer-BioNTech and Moderna together produced the vast majority of the 670+ million COVID-19 doses administered in the U.S., so their dominance in VAERS reports is a direct reflection of their market presence.
Before the pandemic, companies like Merck, GlaxoSmithKline, and Sanofi Pasteur dominated the vaccine market with products covering childhood immunizations, flu vaccines, and travel vaccines. Their VAERS report counts are substantial but dwarfed by the COVID-19 era surge.
High report counts for a manufacturer primarily reflect how many doses they've distributed. A company with 50% market share would be expected to have roughly 50% of reports, all else being equal. Comparing manufacturers on raw report counts without adjusting for doses administered is misleading.
As VAERS reporting normalizes following the COVID-19 pandemic surge, the data landscape for manufacturer landscape and market concentration 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 manufacturer landscape and market concentration 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 manufacturer landscape and market concentration 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 manufacturer landscape and market concentration 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 manufacturer landscape and market concentration 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 manufacturer landscape and market concentration 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.