Cases of Covid-19 are increasing in older age groups as experts warn that the pandemic is not over, Press Association has reported.

New data does indicate a substantial fall in cases since the peak of the Omicron wave in January, however, infections in England are rising among those 55 and older.

Researchers have suggested increasing case numbers in the age group could be down to a factor of things, including more mixing between the age groups since restrictions eased, and the waning of the vaccine booster.

Professor Paul Elliott, director of Imperial College London’s React programme, said it is possible that the figures indicate infections are beginning to rise in England but it is unclear where they will go.

Dr Jenny Harries, chief executive of the UK Health Security Agency (UKHSA), said: “These data confirm that cases have declined substantially following the peak of the Omicron wave.

“However, the increasing presence of the BA.2 sub-lineage of Omicron and the recent slight increase in infections in those over 55 show that the pandemic is not over and that we can expect to see Covid circulating at high levels.

“Vaccination remains the best way to protect us all from severe disease and hospitalisation due to Covid-19 infection. We urge you to come forward for your primary or booster doses straight away if you have not already done so.”

The latest findings from the React-1 study, covering February 8 to March 1 – round 18 of the study, show that prevalence in England during this period was 2.88%.

This was down on the 4.41% reported in round 17 covering January 5 to January 20 2022.

However, it was also the second highest recorded rate of cases since the study began in 2020.

These findings mean that during the period data was collected, around one in 35 people in England had the virus.

Asked whether the increasing numbers of BA.2 could lead to a surge in new cases, Prof Elliott said the data needs to be tracked carefully.

He added: “It is more transmissible.

“We are seeing an uptick in infections, particularly in the older group, and we are seeing an uptick in hospitalisations.

“So I think what we say in our paper is that we really need to be monitoring closely the infection data through surveys, such as React, and we need to monitor the hospitalisations.

“At the moment, we’re possibly seeing the beginning of an uptick, but we don’t know where it’s going to go.”