The prevalence of covid-19 fell by 30% across England, from 132 to 96 people infected per 10 000 between 13 and 24 November, show the latest results from the React study.

More than 105 000 volunteers were tested in England as part of the study, which is carried out by Imperial College London and Ipsos MORI, to examine the levels of infection in the general population. It found that during lockdown the North West and North East of England saw the largest reductions, with infections falling by more than 50%.

However, the researchers warned that national prevalence was still high, with around one in 100 people testing positive, and emphasised the importance of maintaining effective control when lockdown ends.

The advice came after the government announced that the tiered restriction regime will return on 2 December, with most parts of England going into tier 2 (no household mixing but hospitality venues open) or tier 3 (no household mixing, and hospitality venues open for takeaway only).2 However, the measures will be relaxed over Christmas, with three households allowed to meet indoors for the five days 23 to 27 December.

The researchers said it would be crucial to keep prevalence low in the run up to Christmas, to reduce the chances of transmission while the restrictions are relaxed.

Study coauthor Steven Riley, professor of infectious disease dynamics at Imperial College London, said, “My own concern is more about the period from the end of lockdown to the beginning of the Christmas period. That’s a longer period of time, and there is more scope there. We need to keep a close eye on the data streams and make sure that people focus on keeping [infections] low and preserving those gains into Christmas. We are averaging over 400 deaths per day. I know people are used to that figure now, but that is a large number of deaths every day.”

The study results, released as a preprint, are the seventh provided by the React study, which has been conducting polymerase chain reaction tests on random population samples since May 2020. The most recent report found that the prevalence was halving every 37 days and the national R rate was estimated to be 0.88.

Looking at regional data, the researchers found that prevalence halved in the North West (1.08%, down from 2.53%) and North East (0.72%, down from 1.88%) and fell in Yorkshire and the Humber (1.17%, down from 1.8%). But there was little change in prevalence in the East Midlands (1.27%, down from 1.31%), West Midlands (1.55%, down from 1.56%), and London (0.98%, down from 1.03%).

The report also found that people of Asian ethnicity had a higher odds of testing positive than white people, while people living in the most deprived neighbourhoods had higher odds of testing positive than those living in less deprived neighbourhoods. There was also an increase in prevalence among people living in the largest households.

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  1. REACT-1 round 7 interim report: fall in prevalence of swab-positivity in England during national lockdown.
  2. Griffin S. Covid-19: England will return to regional restrictions amid rapid testing push. BMJ2020;371:m4577. doi:10.1136/bmj.m4577 pmid:33234558FREE Full TextGoogle Scholar

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