Norovirus GII.17 Accounts For 75% Of Recent US Outbreaks, Data Show

Medscape (6/17, Splete, Subscription Publication) reports new data published in Emerging Infectious Diseases found that “norovirus GII.17 accounted for 75% of outbreaks in the US in the 2024-2025 season, outpacing outbreaks caused by the GII.4 norovirus.” Data indicate that “norovirus GII.17 accounted for < 10% of outbreaks in the US 2022-23 season, but rose to 75% during the 2024-25 season, passing the number of GII.4 outbreaks.” In addition, “norovirus activity peaked earlier in 2024-25 (accompanying the rise in GII.17) compared to previous seasons. The 2024-25 season peaked in January 2025, vs peak periods in February 2023 and March 2024 when GII.4 still dominated.” The researchers also “observed no regional differences in the distribution patterns of the GII.4 or GII.17 outbreaks.”