This is evidenced by the data for the current 2024/2025 season in England norovirus lab reports are especially higher than the average of 5 seasons. The number of norovirus cases normally increases in the fall and winter, but this 12 months the number of cases increased sooner than usual and is predicted to proceed to extend. This increase is accompanied by a change in circulating common norovirus genotypes.
Data showing growth
Our surveillance systems reveal several key patterns:
- The laboratory confirmed cases of norovirus
Although we normally expect the peak of norovirus cases to occur in the winter months, this season the situation is exclusive and begins sooner than usual. With the exception of a dip during the October half-term school holidays, activity increased again across all age groups. This highlights the significant role that educational settings play in norovirus transmission patterns. However, health and social care facilities also contribute to the spread of the virus, given its highly contagious nature and the vulnerability of those in these facilities.
2. Hospital impact
The impact of the norovirus epidemic on healthcare facilities is critical. The Hospital Norovirus Outbreak Reporting System (HNORS) is reporting more outbreaks than average, although it’s important to keep in mind that reporting to the system is voluntary and levels of involvement may vary. This suggests we could also be heading towards a period of increased pressure on our health and social care infrastructure during an already difficult winter.
3. Genetic diversity
For the first time, genogroup 2, genotype 17, referred to as GII.17, has grow to be the most often detected genotype in England since April 2024. GII.17 now accounts for 66.3% of characterised samples in the 2024/2025 season so far. Previously, GII.4 noroviruses dominated worldwide, and the GII.4/Sydney/2012 variants remain the most often detected variant worldwide as of winter 2012.
Several aspects are likely contributing to the unusual norovirus activity we are seeing this season. These include:
- Post-pandemic changes in population immunity
- Changes in the possibilities of diagnostic tests
- Changes in reporting to national supervision
- There is an actual increase in norovirus transmission attributable to the emergence of GII.17
Key details about GII.17
There is currently no indication that GII.17 causes more severe disease, but work is ongoing to further assess its severity. This latest GII.17 genotype was incorrectly named in Kawasaki media as the historical GII.17 variant and never one other name for the current GII.17. The distinction is significant because incorrect use of “Kawasaki virus” causes confusion with “Kawasaki virus”.Kawasaki disease”, which is an unrelated, very serious condition.
Waiting for something
Earlier this 12 months, our surveillance systems successfully detected a transition from GII.4 to GII.17 dominance, requiring continued attention and shut monitoring by health care providers and public health teams, particularly as we enter the winter season. Because norovirus normally causes short-term illness, many individuals treat it at home without consulting a health skilled – this implies many cases go unreported and don’t show up in surveillance results – so the community burden is prone to be much higher. While the current numbers are higher than expected, they need to be interpreted in the context of changes in surveillance systems and the evolving post-pandemic landscape.
What you may do to stop the spread of norovirus
To reduce the spread of norovirus, wash your hands thoroughly with soap and warm water, as alcohol-based hand sanitizers are not effective against the virus. Stay home for a minimum of 48 hours after symptoms subside and, if possible, disinfect surfaces with a bleach-based cleaner. Full instructions may be found here.
