Experts have been stumped by a recent rise in Covid cases and hospitalisations in England, according to reports.
Figures published by the React and ZOE Covid studies have shown cases rising in all age groups and regions of the country, with the government’s own dashboard showing 71,259 cases were picked up on Thursday.
Case rates were highest in those aged 30 to 39, with a weekly rate of 542.7 per 100,000 population.
The hospital admission rate for England also rose, from 9.84 per 100,000 in the previous week, to 11.26.
“The one thing we do know is that both cases and admissions are rising, seemingly across all age groups and regions. What we don’t understand is exactly why,” said Christina Pagel, a professor of operational research at University College London (UCL).
The lifting of all Covid restrictions has made it more difficult to properly track and understand the country’s epidemic, scientists warn.
Professor Irene Petersen, an epidemiologist at UCL, said that scientists had been caught off-guard by the recent rise in hospital admissions.
“As close contacts are no longer encouraged to test it is likely that there are fewer people who realise that they are infectious and therefore not testing,” she said.
She also speculated that “one of the reasons why we see an increase in hospitalisations now is not so much because of the waning in the triple vaccinated, but in the double vaccinated”.
Some 33 per cent of all people aged over 12 have yet to receive a third dose, government data show.
Paul Hunter, a professor in medicine at the University of East Anglia, also tweeted that the recent increase in hospital admissions had “taken me by surprise”.
However, experts have said that, for now, the rise in hospitalisations is being driven by Covid-positive people who are seeking care for a separate health issue.
The number of patients being admitted because of Covid continues to lag behind, data show.
Prof Petersen said “we may not need to worry too much,” adding that it would be troubling if the number of people admitted to intensive care units “goes up dramatically”.
She said a rise is expected, but the “key is that they are not overloaded”.
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