ST. LOUIS — A study published in the Annals of Internal Medicine by Ziyad Al-Aly, MD, and colleagues indicates that coadministering COVID-19 and influenza vaccines is not linked to an increased risk of adverse events. The findings suggest no heightened risk for serious, life-threatening, clinically important, or less severe adverse events when both vaccines are given simultaneously compared to influenza vaccination alone.

The study utilized a target trial emulation design, drawing upon electronic health data from the Department of Veterans Affairs. Researchers assessed 46 individual adverse events, and after correcting for multiple comparisons, no reported adverse events showed statistical significance. Myocarditis risks were small in both the coadministration and influenza vaccine-only groups, with a risk difference of 1.11 (95% CI -0.87 to 5.26).

The coadministration group included 705,124 individuals who received both COVID-19 and influenza vaccines on the same day. For comparison, 1,813,205 people received only an influenza vaccine. The mean age in the coadministration group was 69.7 years, while the influenza vaccine-only group had a mean age of 68.4 years. Across both groups, 92.7% of participants were male, and between 72% and 78% were white.

Al-Aly stated that the study found no evidence of increased risk. "We looked at 46 different outcomes -- literally leaving no stone unturned -- and we came up empty-handed." In the coadministration group, 58.8% received high-dose influenza vaccines, while 51.1% in the influenza-only group received high-dose formulations. For COVID-19 vaccines in the coadministration group, 60.4% received the Moderna vaccine, 39.2% received the Pfizer vaccine, and 0.46% received other COVID-19 vaccine formulations.

The study incorporated data from three COVID-19 vaccine formulation eras spanning September 2022 to August 2025: bivalent vaccines, XBB-adapted vaccines, and KP-adapted vaccines. The researchers did not measure short-term adverse events such as transient fever or injection site pain. Al-Aly noted the continuing safety record of vaccines. "Even in today's world, where people have been exposed to multiple prior COVID-19 vaccines and their immune systems have been shaped by at least one COVID-19 infection, vaccines have a reassuring record of safety."