Snow might not be swirling in the UK but Covid is in the air this Christmas, data has revealed, with experts warning a new variant is on the rise around the world. According to data from the Office for National Statistics (ONS) and the UK Health Security Agency (UKHSA), an estimated 4.2%, or one in 24 people, in England and Scotland had Covid on 13 December compared with 1.8% – or one in 55 – on 29 November. The data is based on self-reported lateral flow device (LFD) results from about 150,000 participants across England and Scotland, who provide up to 30,000 test results a week. It also revealed that while prevalence had increased across all age-groups, it was higher in those between 18 and 44 years old than for those over 65 years old. “The prevalence has increased in every English region over the past two weeks and in particular London and the south-east,” the report adds. The figures come days after the World Health Organization (WHO) said a new subvariant of Omicron, labelled JN.1, had been classified as a “variant of interest” after spreading rapidly in the Americas, western Pacific and European regions. The sub-variant has already turned up in countries from the US to Singapore and the UK – where it accounted for 43% of sequenced cases as of 16 December. JN.1 is closely related to another variant called BA.2.86, or Pirola, and both were previously tracked together. According to the US Centers for Disease Control and Prevention (CDC), JN.1 and BA.2.86 differ by a single change in the spike protein of the virus. The CDC said: “The continued growth of JN.1 suggests that it is either more transmissible or better at evading our immune systems. At this time, there is no evidence that JN.1 presents an increased risk to public health relative to other currently circulating variants.” The CDC said at present there was no evidence JN.1 was associated with increased severity of disease, and that updated Covid jabs were still expected to offer protection. However, the WHO said JN.1 could cause an increase in Covid cases at a time when other viral and bacterial infections were surging, especially in countries entering the winter season. Christina Pagel, a professor of operational research at University College London, suggested JN.1 was likely to cause a wave of infections second only to that recorded in England in March 2022, which was driven by the Omicron variant. “After a quieter 2023, it’s a sign that we can’t just assume that Covid has gone away or can’t cause us significant issues any more,” she said, adding as many people had not been eligible for recent booster programmes, they had not had a Covid vaccination for two years. “This will likely mean they feel sicker [if they do catch Covid] and also [have an] increased risk of long Covid too,” Pagel said. “Given we’ve got millions of leftover vaccines from the autumn booster campaign, why not try to put them in people’s arms instead of the bin and open them out to the general population?” Prof Stephen Griffin, a virologist at the University of Leeds, also raised concerns about restricted access to boosters, and stressed that the longer-term consequences of Covid infections had not been properly accounted for in the way the UK was handling the pandemic. “The accumulative damage to health, with a disproportionate effect on disadvantaged groups, is profound,” he said. Dr Simon Williams, a psychologist at Swansea University, said reduced uptake among those eligible for Covid jabs this season meant the proportion of the high-risk population that could experience severe Covid was higher than last year, while behaviours such as mask-wearing or staying away from others when sick had dramatically declined. “It’s not a bad thing that people, in general, are able to live normally. However, there is still an argument for picking back up some of the protective behaviours when we need them – specifically at this time of year – and then loosening them when prevalence drops back down again,” he said. Prof Steven Riley, the director general for data and surveillance at UKHSA, urged those who were eligible to have their latest vaccinations, and said people with symptoms of respiratory illnesses, including Covid, should try to limit contact with others as much as possible, particularly if contacts were older or more vulnerable. “At this time of year, the cold weather, shorter days and increased socialising mean that the potential for transmission of respiratory viruses like Covid-19 is particularly high,” he said. “This, as well as the possible impact of new variants, means it’s not unexpected to see cases increasing.”