Scientists have said that the UK should include re-infections in its Covid figures as soon as possible, despite warnings that up to 15% of Omicron cases could be people who have had coronaviruses before.
The daily Covid case figures do not include re infections for all countries of the UK.
If the positive tests are more than 42 days apart, the figures for Wales include multiple cases for the same person.
The proportion of cases that are reinfections is growing and scientists say the figures should be updated.
The re-infection rate with Delta was fairly low, but is higher now because of a bigger pool of people with prior infections.
According to a report released by researchers at Imperial College London last month, the risk of reinfection with Omicron is more than five times higher than with Delta.
Prof Neil Ferguson of Imperial College said that between 10% and 15% of Omicron cases are reinfections.
The data released by the UK Health Security Agency shows that of 116,683 people identified as having an Omicron infection in England between 1 November and 18 December last year, 11,103 had previously tested positive for Covid more than 90.
The government did not include re infections in the case figures it published at the start of the epidemic as it was not certain if it was possible to be re-instated after a while.
The case data should now be updated according to Tim Colbourn, professor of global health systems, epidemiology and evaluation at University College London.
He said that reinfections should be added to the dashboard as soon as possible as they will be a growing proportion of cases going forwards. I think the proportion will increase over the coming weeks as immunity from prior infections fades.
Prof Christina Pagel, director of the Clinical Operational Research Unit at the University College London, agreed that the proportion of Covid cases that are reinfections will continue to grow, although the rise is going to be modest now that Omicron is the dominant variant in the UK.
It is important to include re infections in order to understand how quickly an immune-evasive variant is spreading.
She said that it will be rare to find someone who has never had Covid, given current policies.
The UKHSA is planning to include reinfections in case data from the end of the month, though Pagel said the task is not simple.
She said that most of the complex data tables that underlie the dashboard need to be changed to include reinfections.
