The first national snapshot of Covid-19 rates has revealed that 148,000 people in England were infected with the virus over the past two weeks.
The study, by the Office for National Statistics (ONS), tested 10,705 people in more than 5,000 households and estimated 0.27% of the population in England were currently positive for Covid-19. The analysis suggests about 148,000 people across the entire population would have tested positive on any day between 27 April and 10 May 2020.
The findings will inform the government’s next steps as it considers whether it is safe enough to further ease restrictions on socialising, businesses and schools in the coming weeks. 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 potential of opening primary schools on 1 June to fuel transmission in the community, as 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 also reveals far higher infection rates among those working with patients in healthcare and those in social care roles, with 1.33% of these participants testing positive.
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.
Paul Hunter, professor in medicine at the University of East Anglia, said the figures show that “we’re still some way off getting to a point where we can relax restrictions a lot”.
Sources close to Downing Street say the target for new daily infections is 5,000 before the lockdown can ease, but other more cautious voices in government are understood to be pushing for fewer than 4,000 new cases a day. There is scepticism within the government that the UK will have reached that figure before 1 June, the first possible date for easing the lockdown.
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. And unlike the target of 5,000 cases each day, the latest ONS figures exclude hospital patients, meaning the ONS infection rate is a slight underestimate. So it is difficult to assess from the ONS data how far we are from the 5,000 target.
The ONS survey is expected to give a clearer picture of the country’s trajectory as the current pilot phase of the survey is rolled out to cover up to 300,000 people over the next 12 months. From now on, weekly updates will be published, designed to provide a rolling estimate of current infection levels and community transmission rates.
Future updates are also expected to give regional breakdowns, which could highlight hotspots for infection, as well as the results of antibody testing, showing how many people have been infected in the past.
Azeem Majeed, professor of primary care at Imperial College London, said the data suggested some previous studies, based on hospital admissions, might have underestimated the rates of infection in children.
“The ONS data suggests that these studies did not reflect the true rate of infection in children because they were focused on the sickest patients,” he said. “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.”
The result does not give a direct measurement of R, the effective reproduction number of the virus, which tells us whether the country is on an exponentially increasing trajectory or whether infection numbers are on the way down.
The current number is a snapshot, while R is about the gradient of the curve and is calculated using the current infection rates and other data such as hospital admissions, serology surveys of past infection and behavioural contact surveys.