The survey tested more than 85,000 volunteers between 4 and 13 of February to examine infection levels in the general population.
One of the largest and most authoritative coronavirus surveys has found that infections are quickly falling in England, confirming that lockdown is working to suppress the virus.
Imperial College London’s REACT study found that infections had fallen by more than two-thirds since the last time it reported in mid-January.
Last time, REACT found that 1 in 63 people currently had the virus. This time, it estimates that 1 in 196 people are infected.
This means that infections are now at a similar level to where they were when REACT reported in September.
The researchers estimate that the national R number for England is between 0.69 and 0.76, meaning the outbreak is decreasing across the country.
Professor Paul Elliott, director of the programme at Imperial, called the results “encouraging”, saying they showed that “lockdown measures are effectively bringing infections down”.
He added: “It’s reassuring that the reduction in numbers of infections occurred in all ages and in most regions across the country.”
This uniform decrease in age groups means that there is no evidence that the vaccination programme is behind the fall in infections. If that was the case, the researchers said, they would expect to see a bigger drop in people aged 65 and over.
REACT tested more than 85,000 volunteers between 4 and 13 of February to examine levels of infection in the general population. Its large size makes its findings significant, as does the fact that it has previously reported no drop in infections 10 days into lockdown.
However, the researchers warned that although the trend was good, the level of cases was still too high for comfort, as lots of patients continued to be admitted into hospital.
They warned that any route out of lockdown needed to be “closely monitored”. The prime minister is due to set out his roadmap for releasing restrictions on 22 February.
Experts welcomed the news, but said the REACT study posed questions for Boris Johnson ahead of his announcement, because it indicated possible regional and ethnic inequalities in the fall in cases.
The researchers found that “large household size, living in a deprived neighbourhood, and Asian ethnicity were all associated with increased prevalence”.
Dr Tom Wingfield, Senior Clinical Lecturer and Honorary Consultant Physician, Liverpool School of Tropical Medicine, said: “This again lays bare the unacceptable socioeconomic and ethnic inequalities within our society.
“We need to learn from this as we lift the current lockdown measures and not make the same mistakes again.”
Although the number of infections fell everywhere, the biggest fall was in the south, with a very dramatic fall in London. The areas with the highest prevalence are now the North West and North East. In the North East, the REACT team estimate that R is probably above 1.
This repeats the pattern that emerged following the first lockdown, although experts noted that the other large infection survey, which is conducted by the Office for National Statistics (ONS) did not find a similar regional trend.
“These regional differences are something to keep an eye on as more data emerge from REACT and from the ONS survey,” said Professor Kevin McConway, Emeritus Professor of Applied Statistics at The Open University.
“We’re so lucky here to have both of these surveys, that provide relatively unbiased estimates of infections across England, so that we can see how they compare.
“Most countries of the world don’t even have one such survey.”