# Claim:Hantavirus is a side effect of Pfizer's mRNA COVID-19 vaccine, according to Pfizer’s own internal document listing side effects.

*biotech · news · 2026-05-08 · Snopes.com*

## Key points

- Hantavirus is listed as an adverse event of special interest, not a vaccine side effect.
- Pfizer’s document does not report any actual cases of hantavirus following vaccination.
- Regulatory authorities require pre-set monitoring lists for adverse events, not causality claims.
- Large studies from France and Denmark show no increased hantavirus risk after mRNA vaccination.

**Companies:** Pfizer, BioNTech
**Countries:** United States, United Kingdom

[Read the full story on Snopes.com](https://www.snopes.com/fact-check/hantavirus-covid-vaccine-side-effects/)

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