Moderna says it’s ‘one step closer’ to a norovirus vaccine as the virus spreads across the U.S.

“Stomach bug,” “cruise-ship virus,” “winter vomiting disease”—all are nicknames for norovirus, the top cause of vomiting, diarrhea, and foodborne illness in the U.S. The contagious ailment typically circulates throughout the late fall, winter, and early spring, and the 2024–25 season is no exception. Nationwide test positivity was nearly 23% the week ended Dec. 28, compared to less than 11% six weeks earlier, according to the Centers for Disease Control and Prevention (CDC).