'Infection with BA.5 seems to give some protection against infection with XBB. There is not much difference with severe disease, so we can expect a fair number of infections. Severe disease will continue in known risk groups,' says virologist Dr Gagandeep Kang
Top experts have reiterated the need to be vigilant and avoid panic as the US-based Centers for Disease Control (CDC) and Prevention indicates that the Omicron sub-variant XBB.1.5 has led to a rise in cases in the US. Experts have stressed the need for a higher genome-sequencing in the country as INSACOG (Indian SARS CoV2 Genomics Consortium) data has shown up five positive samples for the XBB.1.5 sub-variant. Says noted virologist, Dr Gagandeep Kang, “XBB.1.5 is now more than two-third of all cases in the USA. Since XBB and further sub-lineages have evolved in immunised populations, we should expect them to be able to infect more easily and that is what they are doing. Infection with BA.5 seems to give some protection against infection with XBB. There is not much difference with severe disease, so we can expect a fair number of infections. Severe disease will continue in known risk groups.”
The XBB.1.5 variant of Covid is actually a sub-variant of XBB. It is a combination of BA.2.75 and BA.2.10.1 and was first reported in India.
It is considered more contagious than BF.7, which is driving the current spate of infections in China. It has a greater immune-escape potential.
According to Sanjay Pujari, member of the Indian Council of Medical Research (ICMR) task force, “the XBB.1.5 is a recombinant of the Omicron’s BA.2 sub-variants. This has originated in the USA and the rate of transmission (RT) is 1.8.
Reports are indicating that most hospitalisations are in the elderly population and those who have not taken the booster dose vaccination. So far in India all five cases had mild illness and have recovered well.” He points out that one cannot generalise how geography-specific sub-variants will behave and hence genomic surveillance is important.
Dr Rajesh Karyakarte, coordinator for genome sequencing in Maharashtra, explains that in the USA, a descendant of XBB — that is XBB.1.5 — is replacing the previously dominating BQ.1 and BQ.1.1 sub lineages. Currently XBB.1.5 is growing in New York ahead of others. “We have already seen in Maharashtra that XBB is the most dominant variant and has not allowed BA.5 and its sublineages like BQ.1 to dominate. XBB already has greater immune evasiveness than others and adds more mutations. For example XBB.1.5 ,” says he.
In Maharashtra, no case of the XBB.1.5 sub variant has been recorded so far. Over the last several months, the state has already reported 270 cases of the XBB and top surveillance officer Dr Pradeep Awate told The Indian Express that there has not been a significant rise in cases. These are sublineages and overall the infection has been a mild one.
Dr Shashank Joshi, noted endocrinologist and diabetologist at Lilavati Hospital, Mumbai, argues for vigilance as there seems to be no clinical correlation in terms of hospitalisation and deaths. “There should be no panic at all as all these are Omicron sub-lineages. However it is important to keep a check on cold, cough and respiratory illnesses which are common this time of the year,” he adds.
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