Boris Johnson will not introduce further Covid restrictions in England before 2022, giving mass events the go-ahead and leaving nightclubs open for New Year’s Eve – in contrast with all other UK nations. Scientists criticised the decision, which came as England recorded its highest number of Covid infections. They said it was the moment of “the greatest divergence between scientific advice and legislation” seen since the start of the pandemic. The announcement came after advisers told Johnson that significant NHS pressures were coming from staff absences rather than overcrowded intensive care units. One model has predicted that in London, where Covid rates are highest, up to 40% of staff could be absent because of sickness. Ministers are expected to continue to focus efforts on vaccination – including the booster rollout. Sources say most of the cases behind the rise in hospital admissions are people who are unvaccinated. The decision not to introduce curbs makes England an outlier in the UK, after Scotland, Wales and Northern Ireland put limits on social gatherings and mass events. Johnson’s cabinet rejected new measures before Christmas, as cases of the Omicron variant started to rise. Three cabinet ministers who spoke to the Guardian on Monday said they remained deeply sceptical that any further measures were necessary. The health secretary, Sajid Javid, said people should take steps themselves to protect others. “We won’t be taking any further measures. Of course people should remain cautious as we approach new year celebrations and take a lateral flow test if that makes sense, celebrate outdoors if you can, have some ventilation indoors if you can,” he said. The call for caution was reiterated by the prime minister in a series of tweets on Monday night. “We will continue to monitor the data carefully, but there will be no new restrictions introduced in England before the new year,” he said. “However, I would urge everyone to continue to act cautiously given the rising number of Omicron cases. “Most importantly I urge everyone to get their first, second or booster jab without delay to protect yourselves and your loved ones.” England recorded 1,281 people admitted to hospital in England on Christmas Day – the most recent available figure – up from 1,020 the day before. Though it is the highest figure since mid-February, it is well below the highest in the pandemic when admissions reached 4,134 last January. Downing Street has been hopeful that if admissions in London stay below 400 a day, NHS capacity should remain stable. According to the latest data, 364 patients were admitted to hospital with Covid on Christmas Day in London, down slightly from a high of 390 admitted on 23 December. Case rates reached a new high of 113,628 on Christmas Day and fell to 98,515 on Monday, though the Scientific Advisory Group for Emergencies (Sage) has previously cautioned that data will be unreliable over the festive period as testing and hospital admission patterns change. Johnson’s decision to rule out further curbs this year came after a crunch summit he chaired online from his Chequers residence, with England’s chief medical officer, Chris Whitty, and the government’s chief scientific adviser, Sir Patrick Vallance. Messaging from government will instead put an emphasis on personal responsibility. “Nothing in the data around hospitalisations is showing we need to put our foot on the accelerator,” a Number 10 source said. “It is not accelerating as quickly as it might have done. We just need to keep a close watch.” Javid said the most recent data showed there were disproportionate numbers of unvaccinated people being admitted to hospital and that there were 1.5m vaccination slots available over the next few days. “Can I please say to people, please do come forward,” he said. “Protect yourselves, protect your loved ones and protect your community.” Officials monitoring the data suggested that although there was a climb in hospital admissions, there was a more positive picture emerging when officials examined how long people were staying in hospital and those admitted to intensive care, along with analysis from the UK Health Security Agency suggesting Omicron was milder. One Whitehall source said the data received by NHS Trusts showed a particularly stark disparity between vaccinated and unvaccinated admissions to hospitals. “Those who are in ICUs are unvaccinated. It really brings home that should be the priority.” Chris Hopson, the chief executive of NHS providers – which represents trusts in England, said there were no reports of large numbers of patients requiring ventilators, and that the main pressure the NHS faced was staffing. “Talking to chief executives this morning, the sense is that admissions are rising but not precipitously so,” Hopson said, adding that a number of asymptomatic patients are being admitted to hospital for other reasons and then testing positive for Covid. “Trusts are not, at the moment, reporting large numbers of patients with Covid-type respiratory problems needing critical care or massively increased use of oxygen, both of which we saw in last January’s Delta variant peak.” Prof Alison Leary, the chair of healthcare and workforce modelling at London South Bank University, said the NHS absence rate in the capital had risen by 30% on normal levels as of Christmas Eve. Leary said one scenario modelled had predicted about 40% of the workforce being absent in London. Though the decision to rule out further restrictions before new year has delighted businesses, the move has divided scientists, several of whom said Johnson was gambling on an unclear picture during a period where data was often unreliable. Simon Clarke, an associate professor in Cellular Microbiology at the University of Reading cautioned that the latest case figures did not include data for samples taken between Christmas Eve and Boxing Day, and that it would only become clear how the virus had moved through the population over the Christmas period in the coming week or so. “While nobody wants to live under tighter controls, the public need to realise that if we end up with a significant problem of hospitalisations and mass sickness, it will be worse than if authorities had acted earlier,” he said. Danny Altmann, a professor of immunology at Imperial College London said: “It does feel hard that, at a time when we need to all pull together to maximise all possible mitigations, we seem to have our greatest divergence between expert clinical/scientific advice and legislation.” Wes Streeting, the shadow health secretary, said the government needed to develop a coherent strategy to combat staffing pressures in hospitals and schools. “The government should publish, as a matter of urgency, the very latest data on hospitalisations and NHS staff absence rates, as well as up-to-date advice from Sage, so that the public can be reassured that they are genuinely following the data and scientific advice and that Boris Johnson is not simply capitulating to his own opponents in the Tory party,” he said.