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.
Influenza vaccines are among the most widely administered vaccines in the U.S., with hundreds of millions of doses given annually. Here's what VAERS data shows about reported side effects.
The most frequently reported side effects from flu vaccines are consistent with known, expected reactions:
VAERS tracks several different flu vaccine formulations. The main types include:
| Type | Reports | Deaths | Hosp. |
|---|---|---|---|
| FLU3 | 119,695 | 1,081 | 8,325 |
| FLU4 | 52,111 | 302 | 2,421 |
| FLUX | 32,816 | 491 | 2,538 |
| FLUC4 | 8,852 | 30 | 204 |
| FLUN3 | 6,739 | 49 | 586 |
| FLUA4 | 4,184 | 43 | 266 |
| FLUN4 | 3,467 | 17 | 154 |
| FLUR4 | 3,407 | 10 | 86 |
| FLUA3 | 3,167 | 10 | 87 |
| FLUC3 | 1,689 | 7 | 62 |
| FLUR3 | 314 | 0 | 4 |
Common and expected (usually resolve in 1-2 days):
Rare but serious (seek medical attention):
Comparing flu and COVID vaccine VAERS reports is a common but misleading exercise. COVID vaccines had dramatically higher reporting rates due to mandatory reporting requirements, heightened public awareness, and the emergency use context. Our COVID vs Flu comparison explores this in detail.