Experts concerned as many nations see Omicron BA.2 surge

Geneva: Health experts worldwide are concerned about the subvariant BA.2 of the Omicron, while the main variant of the same has relaxed its clutches and is rapidly decreasing, churning out positive cases, The Indian Express reported.

The new subvariant is spreading fast in South-East Asian countries like India, Pakistan and China, World Health Organisation (WHO) has recently reported.

WHO's February 15 weekly Covid-19 epidemiological update said that despite the overall number in positive case pool coming down compared with the week before and Delta variant also declining, BA.2 is prevailing globally as per data submitted ate GISAID. The increase in the variant has reached 21.09 per cent, the report said.

Experts say that there is difficulty detecting the subvariant since the S-gene Target Failure criterion fails to detect it most of the time. The method is used to distinguish the original variant of Omicron from other variants, but experts add that existing Covid-19 tests like PCR, antigen and antibody tests have proved effective in finding the subvariant.

Though BA.1 variant, the original Omicron strain, is the dominant strain, BA.2 is found to be spreading fast, including in countries where Omicron cases are declining.

BA.2 has been reported to increase in India, China, Pakistan, Bangladesh, Denmark, Nepal, Brunei Darussalam, Guam, Montenegro, Philippines, South Africa, the UK and USA, according to the WHO report. The subvariant is recorded as 44.7 per cent in South Asian countries.

Initial data suggests that BA.2 is more transmissible than BA.1, while a recent study that is not peer-reviewed yet stated that the former might cause severe disease too. But WHO has not validated the finding yet.

In the case of vaccine efficacy, initial study data says that it will be the same for BA.2 as it was for BA.1, though some studies suggest that vaccines are more effective against the subvariant than the original. Efficacy of treatments is also found similar to that of BA.1.

The Omicron has numerous lineages and out of which B.1.1.529, BA.1, BA.2 and BA.3 are being monitored by WHO. BA.2 is similar to BA.1 in many mutations, but there are differences between them too, for instance, in the spike protein, WHO informed.