Norovirus cases have surged this winter amid the spread of a new variant named GII.17, health officials have warned.
Figures published by the UK Health Security Agency (UKHSA) show that 2,419 cases were reported in the two weeks up to October 20, more than double the average of 993 infections reported in the past five years.
Two-thirds (67 per cent) of new cases belonged to the GII.17 variant, which is one of three forms of the virus along with GI and GIV.
Overall norovirus infections have decreased slightly in the past week, which the UKHSA said was likely due to schools being on half-term and children not spreading the virus inside classrooms.
Norovirus is the most common infectious cause of vomiting and diarrhoea. Other symptoms include a high temperature, headaches, and aches in the harms and legs.
It spreads easily through contact with someone who has the virus or with contaminated surfaces.
While most people make a full recovery within two or three days, the virus can lead to dehydration, especially among the very young, the elderly or those with weakened immune systems.
People with the vomiting bug are urged not to return to school or nursery until 48 hours after symptoms have stopped.
Amy Douglas, epidemiologist at UKHSA said: “The half-term school break is likely to have interrupted the upward trend we’ve been seeing recently in norovirus levels, but cases are likely to rise again as we head towards Christmas.
“To help reduce the spread of norovirus you can take steps to avoid passing the infection on. If you have diarrhoea and vomiting, do not return to work, school or nursery until 48 hours after your symptoms have stopped and don’t prepare food for others in that time either. If you are unwell, avoid visiting people in hospitals and care homes to prevent passing on the infection in these settings.
“Washing your hands with soap and warm water and using bleach-based products to clean surfaces will also help stop infections from spreading. Alcohol gels do not kill norovirus so don’t rely on these alone.”
The UKHSA has said that norovirus activity had been unpredictable since the Covid pandemic, which impacted transmission of most seasonal viruses and led to waning population immunity.
The virus tends to peak in the winter months and causes pressure on hospitals, costing the NHS an estimated £100 million a year.
Older adults and immunocompromised patients are usually at higher risk of severe complications and death from norovirus, with around 80 fatalities per year in the UK and about 200,000 deaths globally.
Around two-thirds of outbreaks are in care homes but places such as hospitals, nurseries and schools are also at risk.
Last month, health officials announced that the world’s first trial for a norovirus vaccine would go ahead in the UK.
The new mRNA vaccine from Moderna will enter final stages of testing within the next two weeks, with results so far showing it creates a “strong immune response”.
Experts believe the vaccine could stop people developing the vomiting and diarrhoea bug, which is linked to around 12,000 hospital admissions in the UK every year.
Currently, the only treatment available for people with serious illness in hospital is intravenous fluids.
