A resurgence of Covid cases is under way across the UK, with infections in the over-70s at a record high and school leaders fearing that preparations for A-levels and GCSEs are being disrupted by outbreaks among staff and students. Based on random swab tests taken in the community, the Office for National Statistics (ONS) estimates that almost 5% of the population in England, or 1,544,600 people, had Covid in the week ending 12 March, and 3.5% of people in the oldest age group. Infections also reached a record high in Scotland, where one in 14 tested positive. The high prevalence among older people has prompted unease, after reports this week that vaccine immunity declines steeply in care-home residents. It is six months since many people in this age group had their last vaccine dose. “Older age groups, especially people who have been isolating for so long, are now quite vulnerable even if they have kept up to date with their vaccines,” said Paul Hunter, a professor of medicine at the University of East Anglia. The increase in infections is being driven by the more transmissible Omicron BA.2 variant, which has become the dominant strain across the UK. It transmits more readily than the original BA.1 strain but there is good cross-immunity between the two variants. “It’s basically sweeping up everyone who didn’t get Omicron the first time around,” Hunter said. This, he added, meant the current wave was more likely to follow a short, sharp trajectory as seen in Denmark and the Netherlands where there had been an Omicron BA.2 wave. “It wouldn’t surprise me if it peaks before the end of March,” he said. Prof James Naismith, a director at the Rosalind Franklin Institute at the University of Oxford, noted the higher prevalence in Scotland than England despite its more stringent rules, including a continued mask mandate in shops and on transport. “My main concern is for the vulnerable, for whom this disease is serious and for those whose lives will be blighted by long Covid,” he said.. “Every effort must be made to triple-vaccinate as many people as possible, quadruple-vaccinate the most vulnerable and make available antivirals.” Sarah Crofts, the head of analytical outputs for the ONS Infection Survey, said: “These latest figures show further increases in infections across most of the UK with high levels of infection everywhere, and in Scotland the highest our survey has seen. “It’s notable also that infections have risen in all age groups, with the over-70s reaching their highest estimate since our survey began.” Schools in England have recorded rising numbers of Covid cases and absences as part of an “exit wave” of Omicron-variant infections. It comes after the ending of most safety measures in schools, including requirements for students to take twice-weekly tests. Attendance data compiled by FFT Datalab shows that pupil absences in England are rising nationally for the first time since January. The south-west, including Cornwall, shows the highest rate of pupil absences, with nearly 10% of secondary school students off midway through March. Tretherras secondary school in Newquay told parents this week that entire year groups would have to stay at home and learn remotely because more than 30 staff members were absent, including 22 with confirmed Covid cases. Parents were told that sixth formers in year 12 were to work from home on Monday, following years 9 and 10 students working remotely this week. “Please know that closing a school bubble is a last resort, and we have looked at alternative solutions and year groups, however, due to staffing implications this is not possible,” the school’s executive headteacher told parents. Richard Lander school in Truro has also had more than 30 staff members off sick, the majority Covid-related, forcing it to tell students in years 8, 9 and 10 to work from home until next week. Headteachers said supply staff remained hard to find, with schools prioritising teaching for students taking A-level, BTec and GCSE exams starting in eight weeks time. “We are dealing with unprecedented levels of staff absence due to Covid, and despite our best efforts to ensure that all our students have a specialist, known teacher in front of them – or indeed a supply teacher – we have reached a point where sadly it is not possible,” said the head of one school who is organising a rotation of year groups working remotely. Caroline Derbyshire, the chair of the Headteachers Roundtable group and executive head of Saffron Walden County high school in Essex, said her trust has had as many staff off with Covid in the four weeks since self-isolation and testing measures were ended as the previous 12 months. Kevin Courtney, the joint general secretary of the National Education Union, said: “At such a critical time, with exam season looming, leaders are now faced with challenges on staffing and in some cases a sudden increase in remote learning. “The government should reconsider its decision to end regular testing in schools and must certainly drop its premature proposals to start charging for test kits. ” The provision of free Covid tests for the public in England is expected to end on 30 March.