Mutant H3N2 flu is hitting the UK hard, with the strain having mutated seven times over the summer. Now experts have warned that eligible members of the public should get their flu jab
A super flu strain in the UK is making more people vomit bile, according to experts.
Health officials have warned that the H3N2 variant is hitting harder and affecting appetite. Reports suggest the H3N2 strain may be more severe than usual because genetic mutations have made it “hotter” and “nastier,” leaving people more vulnerable to infection. Research shows it can cause worse body aches, sudden fatigue, and flu symptoms that come on quickly.
Patients have repeatedly reported vomiting up “yellow bile” as a key symptom of their flu infection. Leading virologists believe this could be due to the flu affecting appetite more than usual, meaning people are vomiting on an empty stomach.
Those with symptoms such as coughs, sore throats, or a runny nose have been advised to limit contact with vulnerable groups, including the elderly, pregnant women, and individuals with underlying medical conditions, due to the risk of severe illness.
READ MORE: ‘My abusive ex left me paralysed after I refused to kiss him on New Year’s Eve’READ MORE: Heartbroken son’s ‘gut feeling’ when he got call about dad on Christmas Eve
Dr Simon Clarke, an infectious disease expert at the University of Reading, told the Daily Mail: “Vomiting bile happens because someone is vomiting on an empty stomach.”
Professor Paul Hunter, a leading infectious diseases expert from the University of East Anglia, told the publication that vomiting yellow bile happens after throwing up on an empty stomach “because of inflammation of the stomach lining. It is often mistakenly called ‘stomach flu’, but you can get it as part of the flu.” He also noted that vomiting yellow bile is a key symptom of gastrointestinal viruses, including norovirus and rotavirus, which are circulating at lower levels for this time of year.
Other flu symptoms can include muscle aches, high temperature, weakness, exhaustion, and a dry cough. Symptoms often come on suddenly and require rest in bed. Professor Stephen Griffin, an expert in virology at the University of Leeds, told the Daily Mail that for those suffering from vomiting yellow bile, “it’s key they do their best to stay hydrated. Drink lots of water, even if it’s coming back up, as you will absorb some.”
Health chiefs sounded the alarm in November 2025 over the early surge in flu cases. Experts believe this may be because the H3N2 strain mutated seven times over the summer. UK Health Security Agency (UKHSA) data showed that the majority of influenza viruses subtyped were H3N2. Hospital admissions for flu in England stood at 3.8 per 100,000 people in early November, up from 2.4 the previous week (end of October). The agency said this level of admissions was usually expected in December. At the time, flu rates remained over three times higher than normal for that time of year, with the highest rates in children and young people.
Health officials have urged those eligible to come forward for Covid and flu jabs to reduce the risk of severe illness and hospitalisation. Top-up doses are being offered to over-65s, care home residents, frontline health and social care workers, and pregnant women. The vaccine design was decided in February to allow time for production, but because the mutant variant did not appear until June, it is not expected to offer full protection against the strain. Experts caution that the vaccine is still vital to reduce severe victims and prevent infection.
Despite a drop in hospital admissions for flu over Christmas week, England’s top doctor has warned the NHS is “far from complacent” as freezing temperatures increase pressure on services. New data published last week showed that, last week, 2,676 patients were in hospital with flu, down from 3,061 the week before, helped by NHS staff vaccinating over half a million more people compared with last year. Demand remains high, with NHS 111 answering 414,562 calls over Christmas.
Professor Meghana Pandit, NHS National Medical Director, said: “It is welcome news to see a drop in the number of people being admitted to hospital with flu…the NHS is far from complacent as temperatures drop, with this likely to increase pressures in the New Year… If you haven’t had your flu jab yet and are eligible, please come forward – it’s not too late.”
Health Secretary Wes Streeting added: “We still face intense pressures… it is more vital than ever that those eligible get their flu jab and people only attend A&E in an emergency.”
READ MORE: Woman threatened ‘you’ll kiss the devil’ before running over and killing boyfriend
