A combination shot would make it easier for people to get vaccinated against Covid and the flu at the same time.

Moderna’s combined Covid and flu shot outperformed the existing standalone vaccines for both viruses, according to the results of a phase 3 clinical trial published Wednesday in theJournal of the American Medical Association. 

The vaccine uses the same messenger RNA technology as Moderna’s approved Covid vaccine.(There are no approved mRNA-based flu shots.)

The trial, funded by Moderna, included more than 8,000 adults ages 50 and older who were enrolled in October and November 2023. For people ages 50 to 64, the new vaccine was compared to Moderna’s Covid vaccine and the flu shot Fluarix. For people 65 and older, it was compared to the Covid vaccine and a different flu shot, called Fluzone, which is a stronger dose typically given to older adults. The trial participants either got the existing shots, or the new combination vaccine plus a placebo shot. (This way, both groups got two injections.)