Increasing Predominance of Norovirus GII.17 over GII.4, United States, 2022-2025

Emerg Infect Dis. 2025 Jul;31(7):1471-1473. doi: 10.3201/eid3107.250524. Epub 2025 Jun 2.

Abstract

Norovirus GII.17 outbreaks in the United States increased from <10% during the 2022-23 season to 75% during the 2024-25 season, surpassing the number of GII.4 outbreaks. The norovirus season also started earlier in 2024-25 than in previous seasons. Continued norovirus surveillance is needed to detect and monitor emerging strains.

Keywords: GII.17; GII.4; United States; enteric infections; norovirus; viruses.

Publication types

  • Historical Article

MeSH terms

  • Caliciviridae Infections* / epidemiology
  • Caliciviridae Infections* / history
  • Caliciviridae Infections* / virology
  • Disease Outbreaks
  • Gastroenteritis* / epidemiology
  • Gastroenteritis* / history
  • Gastroenteritis* / virology
  • Genotype
  • History, 21st Century
  • Humans
  • Norovirus* / classification
  • Norovirus* / genetics
  • Phylogeny
  • Seasons
  • United States / epidemiology