Second norovirus wave looms as cases hit record levels, warns UKHSA

The UK Health Security Agency (UKHSA) has issued a fresh warning as norovirus cases continue to rise, with new data showing infections at their highest levels since records began in 2014.

Laboratory-confirmed cases between 3 and 16 February 2025 were up 29.4% from the previous fortnight and more than double (168%) the five-season average for this time of year.

The increase has been particularly severe in hospitals and care homes, with older adults most affected.

A shift in circulating strains is raising concerns that people who have already had norovirus this season may be at risk of reinfection. The dominant strain, GII.17, has decreased in prevalence from 76% in November to 59%, while the previously common GII.4 genotype is rising sharply, now making up 29% of cases - up from 10% three months ago.

Dr Toyin Ejidokun, Consultant in Health Protection at UKHSA South West, urged the public to take precautions, particularly in healthcare settings:

“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.”

Norovirus, sometimes referred to as the ‘winter vomiting bug’, causes symptoms such as nausea, vomiting, diarrhoea, high temperature, abdominal pain, and aching limbs. Severe cases, particularly among vulnerable groups, can lead to dehydration.

While cases typically decline as the weather warms, UKHSA experts caution that it is too soon to say whether norovirus has peaked this season.

They estimate that reported cases represent only a fraction of actual infections, with approximately 288 community cases occurring for every confirmed case - suggesting around 3 million infections annually in the UK.

Increased cases this season may also be linked to improved testing capabilities and changing post-pandemic infection patterns. Lower temperatures and more time spent indoors contribute to the virus’s spread during winter months.