Warning to stay home for 48 hours as highly contagious bug 'increasing again'

People are being urged to stay at home for 48 hours if they catch a highly contagious strain of norovirus. The variant, known as GII.17, has been the cause of the majority of cases so far in the 2024/25 winter season, the UK Health Security Agency said in its weekly winter update on Thursday.

It said norovirus activity was "now increasing again across all age groups, with the biggest increase in adults, particularly adults aged 65 years and over". The two-week period between November 4 and 17, 2024, was 31.6% higher than the previous two-week period, the UKHSA said. Total reports were almost double the five-season average for the same two-week period.

The number of norovirus outbreaks reported to the Hospital Norovirus Outbreak Reporting System (HNORS) since the start of the 2024/2025 season is 19.4% higher than the five-season average, it added. It also said that, while some of the increased reporting may be attributable to the increased use of PCR multiplex technology - a test capable of detecting multiple gastrointestinal pathogens in one go - it "is likely that the emergence of an unusual norovirus genotype, GII.17, as well as changes in the epidemiology following the COVID-19 pandemic and other factors are contributing to the observed rise".

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The UKHSA said that the season so far had seen the majority (89%) of cases being norovirus genogroup 2 (GII), of which the most frequently identified was GII.17 (66.3%). An increase of this variant has also been observed in other counties during 2024 and is being closely monitored, it added, saying that at present there was no indication it leads to more severe illness.

Norovirus symptoms

The UKHSA said norovirus symptoms include nausea, vomiting and diarrhoea, but can also include a high temperature, abdominal pain and aching limbs. Norovirus infections can cause dehydration, especially in vulnerable groups such as young children and older or immunocompromised people, so if you do get ill it is important to drink plenty of fluids during that time.

Amy Douglas, epidemiologist at UKHSA, said: “We continue to see high levels of norovirus circulating in our communities. If you’ve caught the virus, take steps to avoid passing the infection on. If you have diarrhoea or 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.”

COVID, flu and RSV update

The weekly update also explained the latest position on COVID, flu and Respiratory Syncytial Virus (RSV). It said COVID levels were stable, but flu and RSV hads both increased.

It added: "As we are now seeing more emergency department attendances caused by RSV, it’s important to know how to spot the signs. Some of the main symptoms of a serious infection due to RSV include a cough that gets worse, shortness of breath and difficulty feeding. You should seek medical help if you’re worried your child is seriously unwell and further advice can be found on the NHS website."

Dr Alexander Allen, consultant epidemiologist at UKHSA, said: “Flu is the cause of the rise in winter illnesses that we’ve seen in the past week, with emergency department attendances also increasing. Anyone still eligible for the flu, COVID-19 or RSV vaccines should get booked in ahead of the busy winter period, when we expect flu, and other respiratory viruses to spread between people more easily. Vaccination offers the best defence against these diseases, and now is the time to get protected before Christmas.

“If you are showing symptoms of flu or COVID-19, such as a high temperature, cough, and feeling tired and achy, try to limit your contact with others, especially those who are vulnerable. Washing your hands regularly and using tissues can reduce the spread of respiratory illnesses.

“RSV also continues to circulate at higher levels, with increases now seen across all age groups. For the first time this year, we are able to offer an RSV vaccination to anyone who is 28 or more weeks pregnant, along with people aged 75-79 years.”

Since September 1, 2024, pregnant women have been offered RSV vaccination around the time of their 28-week antenatal appointment. The UKHSA said having the vaccine in week 28 or within a few weeks of this will help build a good level of antibodies to pass on to their baby before birth. This will give the newborn baby the best protection, including if they are born early. Those who turn 75 and those age 75 to 79 are also eligible for a free NHS vaccine to protect them from RSV.