England recorded its highest ever Covid-19 infection prevalence in March and cases were still increasing in the over-55s at the end of the month, an Imperial College London survey said on Wednesday, adding that Omicron subvariant BA.2 was now dominant.
Prime Minister Boris Johnson has lifted all Covid-19 restrictions in England, citing the experience with a wave of Omicron infections over new year which saw record cases, but did not produce an equivalent wave of deaths in Britain’s highly vaccinated population.
Imperial’s study showed that the peak in infections in March surpassed the highs of the BA.1 Omicron wave in January, reinforcing findings by the Office for National Statistics (ONS) that cases have hit an all time high.
The Imperial REACT-1 study also found that while cases had levelled off among under-55s by the end of March, they were continuing to rise among those aged 55 and older.
“We don’t yet know when we’ll see a peak in the oldest age group, the 55+, and because those people are at higher risk of severe outcomes, that is a particular worry,” Imperial epidemiologist Christl Donnelly told reporters.
Imperial recorded overall prevalence of 6.37% between March 8 to 31, a rate of around one in 15 people. That compares to a previous record of 4.41% recorded in January.
Among over 55s, prevalence reached a record 8.3% by March 31, which the researchers said could be due to increased mixing from a group that had largely been more cautious during the pandemic as a whole, and the waning protection of booster shots against infection.
The new peak was fuelled by Omicron subvariant BA.2, which accounted for nearly 95% of sequenced samples in the study. The UK Health Security Agency has found that BA.2 has a growth advantage over BA.1, but is not associated with a higher risk of hospitalisation.
It is the last REACT-1 report on real-time prevalence as the government has cut its funding for the survey, though the ONS Infection Survey will continue.