Adverse Event Risk Not Up With Same Day COVID-19, Flu Vaccination

THURSDAY, July 2, 2026 (HealthDay News) — Same-day administration of COVID-19 and influenza vaccines is not associated with increased risk for adverse events, according to a study published online June 30 in the Annals of Internal Medicine.

Yan Xie, Ph.D., from VA St. Louis Health Care System, and colleagues examined 90-day risks for adverse events after coadministration of COVID-19 and influenza vaccines compared with influenza vaccination alone in a target trial emulation. Data were included for 705,124 participants receiving COVID-19 and seasonal influenza vaccines and 1,813,205 participants receiving only an influenza vaccine between Sept. 1, 2022, and Aug. 26, 2025. Ninety-day risks were examined for 46 adverse events grouped into three composite outcomes: tier 1 (serious or life-threatening), tier 2 (clinically significant), and tier 3 (less severe or self-limiting).

The researchers found that the risks were similar between groups for all three composite outcomes. Of the 46 individual adverse events, nominal statistical significance was seen for two tier-3 risks: syncope and tinnitus (risk ratios, 1.09 and 0.95, respectively); after correcting for multiple comparisons, no risks were statistically significant. Neither composite nor individual event estimates supported between-group differences in risk in period-stratified analyses.

“The findings support the short-term safety of coadministration in older adults and may help inform ongoing vaccine policy discussions and individual risk–benefit assessments,” the authors write.

Two authors disclosed ties to the pharmaceutical industry.

Abstract/Full Text