Stealth Omicron: Rising Covid strain BA.2 detected in third of sampled cases in Sheffield

The Omicron sub-variant, officially called BA.2, is now dominant across England, analysis shows.

BA.2 accounted for 57 per cent of cases in England in the last week of February, up from a quarter just two weeks before, according to research by the Wellcome Sanger Institute.

It comes amid a recent rise in both cases and hospitalisations.

In South Yorkshire, the strain is yet to become the dominant version of the disease.

However, the data for the region is scant. Samples of positive Covid-19 patients were taken and tested to see if they were Omicron, BA.2 or another strain.

A total of just 38 samples were taken for Sheffield, in which 14 cases of BA.2 were detected, amounting to 37 per cent.

A similar number of samples were taken for Rotherham, and returned a rate of 37 per cent and 16 per cent repsectively.

The strain was deemed the ‘dominant’ strain for Barnsley, where it was detected in 30 out of 54 cases, amounting to 56 per cent.

Stealth Omicron got its nickname because it is more difficult to differentiate from Delta than the original Omicron variant, BA.1.

It is also more contagious but early studies suggest it carries no greater risk of hospitalisation.

Dr Jenny Harries, chief executive of the UK Health Security Agency (UKHSA), said case numbers were lower than at the peak of the Omicron wave.

She said: “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.”

Professor Paul Elliott, director of Imperial College London’s React programme, said England is also seeing a rise in hospitalisations and warned that the BA.2 variant 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.”

The Wellcome Sanger Institute analysed 27,000 positive Covid-19 tests taken in the week to February 26 to determine which variant they were.