NEW DELHI:A new Omicron sub-variant of Covid-19, dubbed XBB and responsible for a sharp surge in cases in Singapore, is gaining ground in India, with at least 10-15% samples sequenced in the country showing its presence, according to people familiar with the matter.
And while there are no signs in India, yet, of the highly immune evasive BA.5 sub-lineages— BQ.1 and BQ.1.1— that are currently driving cases in the US and Europe, it is only a matter of time before they make an appearance, the people added, asking not to be named.
In the US, CDC said that these two sub-variants together constitute about 10% of the current cases, and in the UK it’s somewhere between 1-2%. From mid-July 2022, positive cases of these sublineages have been reported also from countries including Nigeria, Japan, France, Belgium, Denmark, and Italy.
XBB, which is a combination of Omicron’s BA.2.75 and BJ.1 sub-variants, was first detected in Singapore in August, and has been responsible for a sharp surge in Covid-19 cases in the island nation. “These are all cousins of Omicron after all; only names change with time because WHO reclassifies the mutants on a regular basis depending on the trend,” a member of INSACOG said. “We will be analysing data retrospectively, and there is a high probability that the other sub-variants that are driving the surge in Western countries currently are already present in India. So far, all mutants were reported under BA.2.75.”
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INSACOG, or Indian SARS-CoV-2 Consortium on Genomics, is a grouping of 54 laboratories that monitors genomic variations in Covid-19 in the country. “It (naming of sub-variants) is based on set algorithms. The moment a new name gets added, the previous strains are accordingly reclassified,” the person cited above added. “That is the reason we may find some of these new mutants already in our system.”
Nearly 11% of samples sequenced are of BA.5 that was first detected in India in May; BQ.1 and BQ.1.1 are its sub-lineages. Most of these samples are from Maharashtra and West Bengal. In a preprint paper on Imprinted SARS-CoV-2 humoral immunity induces convergent Omicron RBD evolution– scientists from various Chinese institutes call XBB the most antibody evasive strain tested. XBB seems to be on its way to surpass the immune evasive status of BA.2.75.2, they added.
“A couple of weeks ago BA.2.75.2 was shown to be the most immune evasive variant seen to date and replicated. That’s now been surpassed by XBB, which is predicted here may challenge BA.5 bivalent vaccine protection,” tweeted Eric Topol, physician scientist who has been analysing data related to Sars-Cov-2 extensively.
Overall, BA.2.75 continues to be the dominant variant in India, according to the INSACOG member. The data from the genome sequencing laboratories is analysed as per the field data trends to study the linkages between the genomic variants and epidemiological trends.
According to experts working for the consortium, this helps to understand super spreader events and outbreaks, and strengthen public health interventions across the country to help in breaking the chains of transmission. Linking this data with the Integrated Disease Surveillance Programme data and patient’s symptoms allows a better understanding of the viral infection dynamics, morbidity and mortality trends.
“This is an RNA virus; therefore it will mutate at a greater rate. What we need to see is if the mutations are virulent enough to cause severe disease needing hospitalisation, or is leading to more deaths. Looking at the clinical impact, we are not seeing increased hospitalisations. Most patients are testing at home and recovering at home. There is no sign so far that there is anything to worry,” said Dr GC Khilnani, former department head, Pulmonology, All India Institute of Medical Sciences, Delhi.
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