Covid-19: Infections in England reached record high in March, finds React study

Covid-19 infections in England reached an “unprecedented” level last month, with prevalence higher than at any other time during the pandemic, the Real Time Assessment of Community Transmission (React) monitoring study has reported.1

Covid-19 prevalence was 6.37% between 8 and 31 March 2022, based on samples from over 100 000 people. This is more than twice the 2.88% in February 2022 and exceeds the previous high of 4.41% recorded in January 2022 during the peak of the first wave of omicron.

Of 4038 positive samples that were sequenced in the latest round of the Imperial College London and Ipsos MORI study, most (3035, 89.7%) were the BA.2 subvariant of omicron.

“We observed unprecedented levels of SARS-CoV-2 infection in England in March 2022 and an almost complete replacement of omicron BA.1 by BA.2,” concluded the study, published as a preprint on 6 April.

“The high and increasing prevalence in older adults may increase hospital admissions and deaths despite high levels of vaccination,” it warned.

In the final round of the study, which is ceasing after its funding was withdrawn by the government, 109 459 people swabbed themselves at home, and 6902 samples showed positive when analysed by polymerase chain reaction, yielding a weighted prevalence of 6.37% (95% credible interval (CrI), 6.21% to 6.53%).

Prevalence of SARS-CoV-2 infection was increasing overall (reproduction number R=1.07, 95% CrI, 1.06 to 1.09), but the greatest increase was in those aged over 55 years (R=1.12, 95% CrI, 1.09 to 1.14). On 31 March 2022, estimated prevalence among the over 55s was 8.31%, nearly 20 times higher than the average for that age group across the whole period from May 2020 through to March 2022.

Paul Elliott, director of the React programme from Imperial College London’s School of Public Health, told a Science Media Centre briefing that he was concerned about the rising prevalence in older adults.

“In children, it seems to have peaked and is turning down. In younger adults, there seems to be a plateauing. But the over 55s seem to be continuing to go up and they are obviously the most vulnerable group.

“I think it’s people mixing more but also we know that many older people had their booster back in October and November last year. So, it’s likely that there is some waning of protection against infection, although there is very good protection against severe illness.”

But he cautioned, “Hospital admissions with covid-19 in England have been increasing in recent weeks, and clearly ongoing surveillance is required both to monitor severe outcomes of covid-19, but also emergence of new variants.”

Prevalence increased in every region when compared with the previous round of the study, with the highest at 8.13% (95% CrI, 7.59% to 8.71%) in the south west.

The decision to remove funding from React means the UK will now solely rely on the covid-19 infection survey by the Office for National Statistics to track prevalence.

Elliott said, “Clearly, we’re disappointed that we’re not going to be in the field anymore, but that’s how it is. We’re very pleased that there’s still going to be some surveillance.”