It has been known that omicron is more able to infect people who have previously had Covid-19 than other variants, due to an innate ability to dodge the immune system.
As a result, reinfections have gone from accounting for a miniscule proportion of all infections, to a sizable chunk.
The latest UK Health Security Agency figures show 11 per cent of all cases were reinfections, but the new study indicates the true figure may be much higher.
However, reinfections are not included in the current daily case figures, an oversight which is now set to be corrected as the UKHSA announced on Tuesday reinfections in England will be included in daily cases from January 31 onwards.
A reinfection will be defined as a person testing positive twice, at least 90 days apart, and the daily figures will be updated back to the start of the pandemic.
Imperial’s study also confirmed that the prevalence of Covid reached an all-time high earlier this month, peaking at more than four per cent of the population, equivalent to around one infected person per 23 people.
Almost all of the positive tests detected though the study were omicron, completely replacing delta.
But throughout January, REACT detected an overall decrease in the total number of infections, and a potential recent plateau.
Sajid Javid, the Health Secretary, said: “It’s reassuring to see Covid-19 infections beginning to slow across the country, as we move back to Plan A.
“Covid-19 rates are still high so as we learn to live with the virus it is vital we continue to be vigilant – wash your hands, let in fresh air, get tested and, if you haven’t already, get boosted now.”