Ministers and scientists are nervous about how far they will be able to ease the lockdown in England at the end of the month, as it emerged that the country needed to more than halve its daily infection rate of around 10,000 new cases a day. A new study from the Office for National Statistics (ONS) suggested that one in 400 people had the virus outside hospitals and care homes over the past two weeks, described by Prof Jonathan Van-Tam, the deputy chief medical officer for England, as “very low” circulation in the community. However, getting the daily infection rate below 5,000 – or even 4,000 – is a main factor in decision-making about lockdown-lifting measures such as opening schools and some shops from 1 June. Two senior government sources said there were still doubts about whether enough progress would be made to allow the reopening of parts of the economy or permit more social contact through the idea of “household bubbles” in the coming weeks. The ONS data, the first national snapshot of Covid-19 rates, also showed children were as likely to catch coronavirus as adults, and that frontline healthcare workers were much more likely to contract it than the general population. It estimated that 148,000 people in England were infected with the virus over the past two weeks, amounting to 0.27% of the population. The figures do not include people in hospital or care homes, where rates of Covid-19 infection – and possibly transmission – are likely to be higher. The Scientific Advisory Group on Emergencies (Sage) discussed expert reports on “bubbles” at a meeting on Thursday, including the New Zealand model of two households joining together to include close family, bring in caregivers, or support isolated people. Evidence from behavioural experts looked at whether it could cause discrimination, how to communicate the policy and how enforceable it would be. In relation to hitting the 1 June lockdown easing date, there remain serious worries about the prevalence of the virus in care homes and hospitals, different levels of infection throughout the country, and whether the contact-tracing and testing regime will be fully up and running. “There is still a lot of uncertainty about how far we will be able to do it,” one senior Whitehall source said. Boris Johnson said in his report on Monday that an easing of the lockdown would be conditional on enough progress being made by 1 June, but his address to the nation raised hopes that some aspects of life could get back to relative normality – albeit with physical distancing – in just two weeks’ time. One of the main deciding factors is whether the daily infection rate falls below 5,000, although some experts believe below 4,000 would be better. A study by Public Health England and the University of Cambridge looking at various models has said the rate could be as high as 11,000 a day. Another major factor is whether the “R rate” of reproduction remains substantially below 1. Sage experts are understood to be looking to publish a range for the R rate on a more consistent basis from next week to increase transparency of the figure, which is sometimes referred to in press conferences but not regularly released. The latest estimate was 0.6 to 0.9. The PHE/Cambridge analysis suggests that transmission rates in London are currently far lower than some other regions, with the study suggesting that there could be as few as 24 new cases each day and an R rate of 0.4. The ONS study tested 10,705 people in more than 5,000 households and suggested about 148,000 people across the entire population would have tested positive on any day between 27 April and 10 May 2020. Experts suggest the current rates of infection remain “some way off” what would be needed to lift the lockdown. The results are likely to fuel concerns about the risk of opening primary schools on 1 June. No evidence was found of differences in the proportions testing positive between the age categories 2 to 19, 20 to 49, 50 to 69 and 70 years and over. The numbers testing positive in this first release were small – 33 in total – and so this picture could change and the figures are expected to be tracked closely over the next two weeks. The study revealed far higher infection rates among those working with patients in healthcare and those in social care roles, with 1.33% testing positive. Previous ONS figures suggested people working in social care in England and Wales were twice as likely to die with coronavirus as the general working-age population, but healthcare workers were no more likely to die than other workers. Paul Hunter, a professor in medicine at the University of East Anglia, said the figures show “we’re still some way off getting to a point where we can relax restrictions a lot”. The latest figures would suggest a “crude estimate” of 10,000 new cases each day, according to Hunter. However, a more accurate calculation would take into account the average number of days over which a person would test positive and other factors. The current pilot phase of the ONS survey will be rolled out to cover up to 300,000 people over the next 12 months. From now on, weekly updates will be published including regional breakdowns. Azeem Majeed, a professor of primary care at Imperial College London, said the data suggest some previous studies, based on hospital admissions, may have underestimated the rates of infection in children. “Children usually have mild symptoms and therefore may not often need medical care. The next step will be to try to determine whether children are as likely as adults to infect other people,” he said.