Health authorities across the United Kingdom are sounding the alarm over a dramatic surge in flu cases, warning that this winter could bring the most severe outbreak in decades. A dominant and "unpleasant" new strain of the virus, known as H3N2, is driving a 56 per cent increase in hospital admissions compared to the same period last year, placing immense strain on the NHS ahead of the Christmas period.
Understanding the H3N2 Threat
The H3N2 strain, also referred to as subclade K, is currently the most dominant influenza variant circulating in England, according to the UK Health Security Agency (UKHSA). Dr Giuseppe Aragona, a GP and medical adviser for Prescription Doctor, explains that the letters and numbers denote the virus's surface proteins. He notes that this specific combination can lead to more severe illness, particularly among older adults and individuals with pre-existing health conditions.
"H3N2 changes regularly, so the version of the virus circulating this year may be different from previous years or from the one in the seasonal vaccine, which can make people more susceptible," Dr Aragona stated. This evolution is a key reason experts believe the UK is facing a particularly challenging season.
Symptoms and Current Rates
Symptoms of H3N2 develop rapidly and are similar to typical seasonal flu, but often with pronounced extreme tiredness. Key signs include:
- Fever
- Cough
- Runny nose
- Body aches
- Potential vomiting or diarrhoea
The data is stark. NHS England figures show that every day last week, an average of 1,717 patients were admitted to hospitals in England with flu. This is not only a 56% year-on-year rise but also a rate seven times higher than in 2023. The situation follows the largest flu season on record in Australia, a region often seen as a predictor for the UK's winter health challenges.
Prevention and Vaccination Effectiveness
Public health officials are clear that vaccination remains the cornerstone of defence. Dr Thomas Waite, Deputy Chief Medical Officer, emphasised: "Flu can be an unpleasant infection for many and life-threatening for some; vaccination is the best form of defence."
New UKHSA data offers reassurance, showing the 2025-2026 vaccine is currently:
- 70 to 75 per cent effective at preventing hospital attendance in children aged 2 to 17.
- 30 to 40 per cent effective in adults.
Dr Jamie Lopez Bernal, a consultant epidemiologist, called this "reassuring evidence" and strongly encouraged all eligible individuals to get their jab. In addition to vaccination, experts advise maintaining good hand hygiene, covering coughs and sneezes, avoiding close contact with those who are ill, and keeping indoor spaces well-ventilated. People feeling unwell are also advised to consider wearing a face mask in public.
How Concerned Should the Public Be?
While urging vigilance, Dr Aragona advised against panic for the general healthy population, stating flu is usually "manageable" for them. However, he issued a serious warning for vulnerable groups. "For older people, those with chronic illnesses, and other vulnerable groups, H3N2 can be serious, and this season may place extra pressure on the health service," he said.
The NHS is braced for a difficult period, with leaders issuing a "flu jab SOS." Last winter saw around 8,000 deaths associated with flu, and with the season starting early and a mutated strain in circulation, the pressure on services is expected to be significant. The key message from all health professionals is to get vaccinated if eligible, take sensible precautions, and seek medical help early if symptoms become severe.
