A potent and mutated strain of influenza, dubbed a 'super flu', is causing a severe wave of illness across the United Kingdom, with health experts highlighting an alarming symptom: vomiting yellow bile.
Why This Flu Strain Is 'Hotter and Nastier'
Leading virologists warn that the current dominant strain, H3N2, has undergone significant genetic changes. It mutated seven times over the summer, making it more virulent and transmissible. This has resulted in what scientists describe as a "hotter" and "nastier" virus that leaves people more vulnerable to severe infection.
The symptoms are notably intense, coming on rapidly and including high fever, debilitating body aches, sudden fatigue, and a dry cough. However, a distinctive and distressing symptom reported by many patients is vomiting yellow bile.
Understanding the Bile Symptom and Health Advice
Infectious disease specialists explain that vomiting bile is typically a sign of throwing up on an empty stomach. Dr Simon Clarke from the University of Reading told the Daily Mail this occurs because the flu is severely affecting appetite, leaving stomachs empty.
Professor Paul Hunter of the University of East Anglia added that inflammation of the stomach lining contributes to the symptom. He clarified that while often mistaken for 'stomach flu', it can be part of the influenza infection. For those suffering, Professor Stephen Griffin, a virology expert at the University of Leeds, stressed the critical importance of hydration, advising sufferers to keep sipping water even if some is vomited back up.
Health officials strongly advise anyone with coughs, sore throats, or runny noses to limit contact with vulnerable groups, including the elderly, pregnant women, and those with underlying health conditions.
Surge in Cases and the Vital Call for Vaccination
The UK Health Security Agency (UKHSA) sounded the alarm in November 2025 over an early and sharp rise in flu cases. Data showed hospital admissions in England reached 3.8 per 100,000 people in early November, a significant jump from 2.4 per 100,000 at the end of October. This level of pressure is usually not seen until December.
While admissions dipped slightly over Christmas week to 2,676 patients, down from 3,061, the NHS remains under strain. Professor Meghana Pandit, NHS National Medical Director, warned services are "far from complacent" as freezing temperatures threaten to increase pressure in the New Year.
Health chiefs are urgently calling for eligible individuals to get their seasonal flu and Covid vaccinations. The groups prioritised include over-65s, care home residents, frontline health and social care workers, and pregnant women. Experts caution that while the vaccine, designed in February, may not offer full protection against this summer-mutated strain, it remains crucial for reducing the severity of illness and preventing hospitalisation.
Health Secretary Wes Streeting echoed the call for vaccinations, emphasising the continued intense pressures on the health service and reminding the public to use A&E only for genuine emergencies.
