Research involving 2.5 million patients found no increase in serious adverse events when receiving both COVID-19 and influenza vaccinations during the same visit.
RT’s Three Key Takeaways:
- Safety of Coadministration: Receiving COVID-19 and influenza vaccines on the same day does not increase the risk of serious adverse events compared to receiving the influenza vaccine alone, according to a study of 2.5 million patients.
- Consistent Results: Safety outcomes were similar across multiple updated COVID-19 vaccine versions, including bivalent, XBB-adapted, and KP-adapted formulations.
- Clinical Range: The study found no increased risk for cardiovascular, neurological, or immune-mediated disorders during the 90-day period following same-day vaccination.
Same-day administration of COVID-19 and influenza vaccines is not associated with a higher risk of serious or clinically meaningful adverse events, according to a study published in Annals of Internal Medicine.
Researchers from Washington University in St. Louis conducted a target trial emulation using data from 2.5 million patients in the US Department of Veterans Affairs (VA) healthcare system between Sept. 1, 2022, and Aug. 26, 2025. The study evaluated the 90-day risks for adverse events after coadministration of the vaccines across three distinct COVID-19 vaccination periods.
The research team compared more than 700,000 individuals who received both vaccines during the same visit with over 1.8 million people who received only the influenza vaccine. The study examined 46 potential adverse events grouped by severity, including cardiovascular and thrombotic events, neurological disorders, and immune-mediated disorders.
The results showed that same-day vaccination did not increase the risk for these outcomes during the bivalent, XBB-adapted, and KP-adapted COVID-19 vaccine formulation periods. Across the updated vaccine versions, overall safety outcomes remained similar to those of patients receiving only the influenza shot.
The findings suggest that receiving both vaccines at the same visit is safe for adults, according to the study. The researchers noted that these results support the short-term safety of coadministration and may help inform ongoing vaccine policy discussions.
The study was conducted to provide data on the safety of simultaneous administration, which is often recommended to improve vaccination rates and convenience for patients within the healthcare system.
