Harvard researchers might have found a way to prevent COVID, the flu—and maybe even the common cold

In animal studies, a new drug-free nasal spray was 99.99% effective in stopping viruses and bacteria.

Early in the pandemic, researchers at Harvard Medical School and Harvard-affiliated Brigham and Women’s Hospital started trying to develop a new way to block respiratory infections. Now a newly published preclinical study suggests how well their product, a nasal spray, might work. In mice, it was nearly 100% effective at stopping viruses and bacteria from causing infection.