Nurse applying vaccine on patient's arm wearing face mask

The influenza drug Fluzone and a booster shot of Moderna’s COVID-19 vaccine can be given together without concern for reduced safety or efficacy, according to new clinical trial data from pharmaceutical company Sanofi.

Mid-stage results from an ongoing clinical trial shows that patients aged 65 and older have the same immune response to each drug when they are co-administered as when given separately. Safety and tolerability results were similar in either case as well, Sanofi said in a Thursday statement.

The study is the first to provide evidence that supports vaccinating against flu at the same time as a COVID-19 mRNA booster in seniors, and comes in time for the start of seasonal flu vaccination campaigns, the company said.

Moderna’s mRNA COVID-19 vaccine is still being vetted for approval as a booster shot by federal regulators, while Fluzone currently is approved and recommended by the Centers for Disease Control and Prevention to protect older adults against flu viruses.

These trial results reinforce existing co-administration recommendations in the United States, Sanofi said.

“This season, more than ever, it is critical to help protect the older adults, who are at especially high risk for both severe COVID-19 and complications from influenza, which can include heart attacks and strokes,” said Michael Greenberg, M.D., North America medical head for vaccines at Sanofi. 

The study is currently following about 300 older adult participants for 6 months for safety reasons. Participants received two doses of a COVID-19 mRNA vaccine at least 5 months prior to the co-administered vaccination.