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 flu vaccine is unique in VAERS because it has been tracked continuously for over 35 years with annual administration to hundreds of millions of Americans. This provides one of the most robust baselines in the entire VAERS database for understanding normal adverse event reporting patterns.
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):
Adults 65 and older are recommended to receive enhanced flu vaccine formulations that may produce stronger immune responses and, correspondingly, more noticeable side effects:
The higher VAERS death reporting rate for flu vaccines reflects the elderly population that receives them, not the vaccine's safety profile. Elderly adults have high baseline mortality rates, and temporal coincidence with vaccination is expected. See our analysis of the 65+ age group for more context.
Most flu vaccines are produced using eggs, which historically raised concerns for people with egg allergies. Current CDC guidance states that people with egg allergies can receive any age-appropriate flu vaccine without additional precautions beyond the standard 15-minute observation period. For those with severe egg allergies, cell-based (Flucelvax) and recombinant (Flublok) options are available that do not use eggs in production.
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.
The flu shot is recommended annually for nearly everyone over 6 months old. See where it fits on the CDC vaccine schedule and our 2026 vaccine schedule analysis.