Fitter XBB strains seen; XBB.3 leads in India with most cases

Pune: The Omicron subvariant XBB has already acquired more mutations and split into even fitter strains, scientists told TOI on Monday. Till October, India had 71 confirmed cases of XBB-driven Covid infection. The number jumped to 136 on October 23. On Monday, the case count was at 235.

From the XBB group, Indian scientists said XBB.3 has been responsible for the most infections (63%), followed by XBB.2 (21%), XBB (11%) and XBB.1.1 (.4%). "The XBB.3 strain is currently leading the pack in India with maximum cases," a senior scientist with INSACOG confirmed on Monday. XBB - first detected in August and described by WHO as among the most immune-evasive versions of SARS-CoV-2 yet - is being closely monitored by countries in the Asia-Pacific region, including Singapore. But unlike trends in Singapore, India is yet to see a major rise in infections. However, authorities have called for caution. In Maharashtra, the health department has warned a possible XBB-led spike may peak by mid-November.

Dr Sanjay Pujari, a member of the national Covid task force, said, "Genomic surveillance must continue. Impact of these subvariants on illness severity needs to be explored and booster uptake, at least for those at higher risk, needs to improve." Viruses evolve to gain advantages. "At present, XBB sublineages have significant immune-evasion properties. However, the population 'immunity wall' is still potentially effective in preventing severe Covid, except in the elderly, individuals with comorbidities and those who are immunocompromised," Dr Pujari said.