England's Norovirus Outbreak Peaks Early in 2024

The U.K. Health Security Agency says the timing of the typical norovirus seasonal increase and peak of activity varies from season to season.

This season, the increase in reporting has begun earlier than in the last five seasons.

As of November 21, 2024, data derived from the Second-Generation Surveillance System up to week 45 of the 2024/2025 season showed that the cumulative number of positive norovirus laboratory reports in England (3,099 laboratory reports) was more than double the 5-season average for the same period (1,342 laboratory reports).

The most commonly detected norovirus genotype worldwide is genogroup II—genotype 4 (GII.4). Historically, there have been five global GII.4 strain replacement events.

While norovirus vaccines are in demand, developing a broadly effective vaccine remains difficult, owing to noroviruses' genetic and antigenic diversity. However, one vaccine candidate continues pursuing U.S. FDA approval.

In the U.S., HilleVax, Inc.'s HIL-214 virus-like particle bivalent vaccine candidate is designed to prevent moderate-to-severe acute gastroenteritis caused by norovirus. HIL-214 vaccine includes antigens targeting genotypes GI.1 and GII.4.

As of November 2024, HIL-214 has been studied in nine clinical trials but has not been approved for commercial use.