An influential study has shown lockdown measures appear to be working as coronavirus infection levels are falling significantly.

Findings from Imperial College London’s React study show that infections in England declined markedly from January into February.

Their research suggests the prevalence of infection in the community was 0.51%, a fall of more than two-thirds since the last report in January 2021 when 1.57% of people tested positive.

The last time a prevalence at this rate was seen was around late September last year. 

In London, the south-east and the west Midlands, prevalence fell by around 80%, although declines were smaller in the northern regions.

Prevalence fell substantially across all age groups with the highest prevalence among 18 to 24 year olds at 0.89% (0.47%, 1.67%), and those aged five to 12 years at 0.86%. It suggests the fall is because of lockdown rather than the vaccinations that have so far been targetted at older people.

However, the overall rate of infections remains high. According to the preprint, which has not yet been peer-reviewed, the number of Covid-19 cases in hospitals is higher than at the peak of the first wave in April 2020.

The research, which saw more than 85,000 swab tests carried out across England between February 4 and 13, showed that Covid-19 infections dropped to just one in 200 people testing positive.

According to the study, the R number is 0.72 and the number of infections is halving every 14.6 days.

Researchers say there is a strong decline in the prevalence of coronavirus in England among the general population five to six weeks into lockdown, but prevalence remains at levels similar to those observed in late September 2020.

They warn that the effects of easing social distancing need to be closely monitored in order to avoid a resurgence in infections and renewed pressure on health services. 

Steven Riley, professor of infectious disease dynamics at Imperial College London, said: “This is good news.

“This is a better decline than many people would have hoped for, certainly when we were thinking about this at the end of December.”

He added: “This is all very encouraging and it’s definitely good news.

“The note of caution is that clearly there’s still a lot of pressure on hospitals, both in terms of number of new admissions, and in the total number of people in hospitals.

“So the trend is great, but because prevalence is high, there essentially isn’t a lot of headroom – there isn’t a lot of leeway.

“Because if for any reason, we do return to growth then we’re immediately at levels of hospital pressure the same as in the peak of the first one.”

Commenting on what the findings might mean for the easing of lockdown restrictions, Professor Paul Elliott, director of the programme at Imperial College London, said it is a “very delicate balance”.

He added: “We could take a lot of encouragement from the decline that we’re seeing, but I would say we’re not out of the woods yet because the prevalence is still one in 200, and that obviously masks some differences in different areas and between different groups of people.”

Although prevalence fell in all nine regions of England over the same period, there was greater uncertainty in the trend for the north west, north east, and Yorkshire and the Humber, researchers say.

Prof Elliott said: “These encouraging results show that lockdown measures are effectively bringing infections down.

“It’s reassuring that the reduction in numbers of infections occurred in all ages and in most regions across the country.

“While the trends we’ve observed are good news, we need to all work to keep infections down by sticking to the measures which are designed to protect us and our health system.”

Health secretary Matt Hancock said: “These findings show encouraging signs infections are now heading in the right direction across the country, but we must not drop our guard.

“Cases and hospital admissions remain high – over 20,000 Covid-19 patients are in hospital – so it is vital we all remain vigilant and follow the rules as our vaccination rollout continues at pace.

“I urge everyone to continue to stay at home – remember hands, face, space – and get your jab when you receive your invite.