(Bloomberg) -- About 1 in every 24 people in England and Scotland has Covid-19, with London the worst-affected area as the highly infectious JN.1 variant spreads rapidly.

The prevalence of Covid is also highest in people from 18 to 44 years old, according to a joint report by the UK Health Security Agency and the Office for National Statistics released Thursday.

The study — which collects data from as many as 30,000 weekly self-reported lateral flow tests results — was launched in November to aid real-time surveillance of the virus and better understand the winter pressures placed on the country’s National Health Service. 

“At this time of year, the cold weather, shorter days and increased socializing mean that the potential for transmission of respiratory viruses like Covid-19 is particularly high,” said Steven Riley, director general for data and surveillance at the UKHSA. “This, as well as the possible impact of new variants, means it’s not unexpected to see cases rising.” 

Across England and Scotland as a whole, the Covid prevalence rate is 4.2% but higher at 6.1% in London. 

The new data comes a day after the World Health Organization said the highly infectious and immune-evasive JN.1 Covid strain was a “variant of interest.” 

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