Covid infection rates are halving every two weeks thanks to the national lockdown, a study has found.

The research saw more than 85,000 swab tests carried out across England between February 4 and 13 and showed just one in 200 people tested positive for coronavirus.

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

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.

According to the preprint, which has not yet been peer-reviewed, the number of Covid-19 cases in hospitals is higher than at the peak of the first wave in April 2020.

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.

The interim findings from the first half of the ninth round of the study suggest the prevalence of infection in the community in England was 0.51 per cent, a fall of more than two thirds since the last report in January 2021 when 1.57 per cent of people tested positive.

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The last time a prevalence at this rate was seen was around late September last year. Steven Riley, professor of infectious disease dynamics at Imperial College London, said: “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: “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."

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.

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 per cent, and those aged five to 12 years at 0.86 per cent.

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

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.”