A GP has told the Express whether Brits should be worried about the Subclade K, also known as the "Super-K" or "K strain" flu, as concerns about the virus continue to rise. The K strain is a mutated seasonal variant of the influenza A (H3N2) virus that spreads rapidly and early in the season.
Concerns sparked by New Zealand's flu season
Concerns about its effects have been sparked after health professionals in New Zealand warned that the strain had dominated the country's flu season this year. The country's flu season, which starts in May, typically sees around 500 people die from influenza each year, with vulnerable groups, including older adults, pregnant women, and those with underlying conditions, most at risk.
With the strain also present in the UK, a GP has confirmed whether Brits should be worried about the mutated strain.
Doctor's advice on the K strain
"The flu itself isn't a new strain, so I wouldn't call it super," Dr Kafi Osman told the Express. "The concern is mainly that it seems to have spread very efficiently and can partly evade existing immunity, which means more people may get infected at once.
"That can lead to more hospital admissions even if the virus itself isn't necessarily causing more severe illness in each person."
The NHS had previously warned about the K strain that first arrived in the UK late 2025. A government investigation at the time involving 554 individuals with flu discovered that 420 of them were infected with the new K variant of H3N2.
Protection and vaccination programme
However, for the 2026/2027 flu season, the doctor reassured Brits that they "can protect themselves in the usual ways", including by getting a flu jab if eligible, staying home when unwell, avoiding vulnerable people if you have symptoms, and practising good hand hygiene.
"I wouldn't say people should panic," he concludes. "Flu can be serious, especially for older people, young children, pregnant women and those with underlying conditions, but there's currently no good evidence that 'Super-K' is uniquely dangerous compared with other seasonal flu strains."
The NHS flu vaccination programme for 2026 is now open and is expected to close March 31, 2027.
