The XFG strain of Covid-19, also known as 'American Covid' or Stratus Covid, has seen a 230% spike in UK cases in just one month, with hospitalisations rising sharply too.
The UK Health and Security Agency recorded cases rising from 1,374 in August to 4,589 in September. Hospital admissions soared even more dramatically, from 950 to 4,939 over the same period.
Symptoms and emergency warning signs
Symptoms range from scratchy sore throats to diarrhoea, with some requiring emergency attention. The NHS warns people to dial 999 if they experience severe breathing difficulties or other critical signs.
Brits who test positive are advised to isolate for at least five days, with under-18s needing just three days. Anyone with the virus should avoid contact with immunocompromised people for 10 days.
Official response and low overall levels
Despite the recent spike, officials stress that overall Covid levels remain low. Alex Allen, consultant epidemiologist at the UKHSA, said: "While Covid-19 activity has shown some recent increases, cases remain at low levels in the UK."
One social media user who fell ill said: "I was in bed for 30+ hours knocked me on my a*** whatever it was." The strain first emerged in Southeast Asia before spreading globally.
