The UKHSA issued new data on the highly contagious vomiting and diarrhoea bug this week
The UK Health Security Agency (UKHSA) this week triggered alerts for specific demographics who may suffer “severe symptoms” amid a surge of norovirus cases, sparking fears of a fresh outbreak wave of the acute stomach bug. On Thursday, the UKHSA alerted that individuals not exempt from risk even if previously infected, thanks to emerging data evidencing a variety in circulating strains and persistently escalating cases across the country.
It’s the highest spike since records commenced in such a format back in 2014. The agency highlighted that particularly young children, the elderly and those with compromised immune systems could face intense symptoms leading to dehydration.
These are the warning signs to watch for:
– Nausea and vomiting
– Diarrhoea
– High temperature
– Abdominal pain
– Aching limbs
Chief epidemiologist at UKHSA, Amy Douglas, warned: “Norovirus levels are still exceptionally high and now with multiple genotypes spreading at the same time, people could end up getting infected more than once this season. We are seeing the biggest impacts in health and social care settings, such as hospitals and care homes.
“Symptoms of norovirus can be more severe in older adults, young children and those who are immunocompromised. If you have diarrhoea and vomiting, please do not visit hospitals and care homes or return to work, school or nursery until 48 hours after your symptoms have stopped and don’t prepare food for others, as you can still pass on the virus during this time.
“Alcohol gels do not kill norovirus. Wash your hands with soapy warm water and clean surfaces with bleach-based products where possible to help stop infections from spreading.”
According to the UKHSA, lab-confirmed norovirus cases between February 3 and 16 spiked by 29.4% compared to the fortnight prior and were over twice the five-season average (168.0%) for that timeframe.
The surging numbers are causing particular strife in hospitals and care homes, peaking among those aged 65 and above. Typically, norovirus cases drop as warmer weather approaches; however, experts say it’s too early to tell if we’ve seen the worst of it this season.
This season’s heightened activity is linked to the recently surfaced GII.17 genotype. However, recent data indicates an increase in a different but commonly observed genotype – GII.4.
Before the appearance of GII.17, GII.4 was the most frequently detected and increased each winter. Although the GII.17 genotype remains dominant, accounting for 59% of cases, its prevalence has dropped from 76% since November. In contrast, the GII.4 strain has seen a significant rise, now representing 29% of cases compared to just 10% three months ago.
The UKHSA warned: “This means that people who have already had norovirus this season may catch it again, as having one genotype does not fully protect against the other. However, at present there is no indication that either GII.17 or GII.4 leads to more severe illness.
“While it is likely the GII.17 genotype has driven up norovirus cases this season due to a lack of previous immunity, the higher numbers we are seeing may also reflect UKHSA’s improved testing capabilities and changing patterns of infection since the COVID-19 pandemic. Norovirus also spreads more easily in lower temperatures as people spend more time indoors and typically peaks during winter months.”
UKHSA experts estimate that reported cases represent only a small fraction of actual infections. For every case reported to national surveillance, approximately 288 cases occur in the community, suggesting around three million cases annually in the UK.