‘Omicron sub-variant linked to Singapore Covid spike gains ground in India: Official
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, people familiar with the matter said.
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.
In the US, CDC said 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 subvariants, 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 OmiNearly cron 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.”
INSACOG, or Indian SARSCoV-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.”
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 to help in breaking the chains of transmission.
“The percentage of XBB may be rising, but we have not seen any reason to worry in terms of higher hospitalisations or deaths, and the situation is the same in Singapore where there has been an XBB spike; no higher hospitalisation or deaths rate. That aside, we need to be vigilant, and we are closely monitoring the trends,” said the INSACOG member.
India is sequencing between 2,500 and 3,000 samples in a month and has the capacity of sequencing 10,000. The current seven-day average of cases in the country is around 2,500.
Doctors confirm what INSACOG analysis says there is not a rise in Covid hospitalisations.
“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… we are not seeing increased hospitalisations. Most patients are recovering at home…,” said Dr GC Khilnani, former department head, Pulmonology, AIIMS, Delhi.