Covid infections have fallen across much of the UK, according to official figures, but remain high enough to put the health service under “significant strain” in the months ahead, scientists warn. The Office for National Statistics estimates one in 65 people in England had Covid in the week ending 13 November, down marginally from one in 60 the week before. A small decline was also seen in Wales, with rates in Scotland and Northern Ireland broadly level. The new figures, which are for community infections and exclude people in hospitals, care homes and other settings, come as a surge in cases on the continent sent Austria back into lockdown and led Germany’s health minister to warn that a further lockdown there could not be ruled out. Cases have risen sharply since the summer in many European countries in a wave of infections that began in eastern nations and moved steadily west. But while the worst affected countries are bringing in major restrictions to contain the surge, UK ministers are holding off with plan B measures that would bring in vaccine passports, expand mask wearing and encourage more people to work from home. Ministers hope immunity is higher in England than in some other countries because of the decision to open up earlier. “Covid has had more time to wash around in the UK,” said a government source. It is understood Downing Street has been advised of two potential scenarios. Either the colder weather could bring a sharp increase in cases and hospital admissions, as on the continent – and “we have suddenly got a big problem” as a government source put it – or higher immunity levels could let Covid continue to circulate among unvaccinated populations including children, but without leading to a surge in hospital admissions and deaths. It will not be clear for some weeks which trajectory the UK is on. The government was buoyed up by news of the significant impact of a third vaccine dose on immunity – and it is understood ministers expect the independent Joint Committee on Vaccination and Immunisation (JCVI) eventually to recommend expanding boosters to all adults. Meanwhile, government sources point to very high vaccination rates among the oldest people as evidence the vaccine programme is going well. Prof John Edmunds, a member of the Sage committee of advisers, told BBC Radio 4’s the World at One programme that waning immunity could lead to an increase in cases among UK adults. “There’s a risk because of waning immunity in older individuals – and that’s all adults, not just the elderly – that cases could really take off,” he said. “It’s really important that we boost immunity in older individuals and then we might be able to avoid any significant fourth wave. “We’re going to have high levels of infection for many months, so I think the NHS will unfortunately be under significant strain. It may not get to breaking point, where we were close to before, but significant strain for a very long period of time is certainly on the cards,” he said. Sage advised ministers last month that a package of light measures, including more mask wearing and encouragement to work from home, could prevent the need for more drastic action later if cases took off in the winter. While vaccine passports are under consideration, they may not have a rapid impact on case numbers. Mark Woolhouse, professor of infectious disease epidemiology at the University of Edinburgh, said that if the aim was to bring cases down fast, other measures could be more effective. “Vaccine passports are not a very efficient way to do that,” he said. “Requiring negative test results at venues is probably a better bet. That takes the infectious people out of the equation.” Vaccine passports could encourage people to get jabbed, Woolhouse said, but it was unclear what level of restrictions would need to be placed on unvaccinated people to have a substantial effect on uptake. “It’s not a quick or efficient solution and we know there is significant transmission going on in the vaccinated population,” he said.