New Delhi: India reported its first case of the hybrid coronavirus variant XE — a recombinant of two versions of the Omicron strain — in a 50-year-old woman in Mumbai who had travelled from South Africa.
The variant was detected in the latest genome sequencing of the Brihanmumbai Municipal Corporation (BMC) conducted at Kasturba Hospital, the civic body said in a statement.
The woman was a South African national who came to India on 10 February from South Africa and was found to be Covid-positive after being tested on 27 February, the BMC said. She was totally asymptomatic and RT-PCR-negative on repeated testing.
However, health ministry officials said that further analysis by experts at INSACOG — a consortium of Indian labs monitoring Covid variants circulating in India — has inferred that the genomic constitution of this variant does not correlate with the genomic picture of the XE variant.
The new variant
Recombinant variants are new strains of the virus that are created by genetic mutations from two different variants.
Recombination can occur when two variants infect the same host cell. The exchange of genetic material between Covid variants occurs because of the way that RNA viruses copy genomes. During replication, the enzyme that the viruses use for replication can end up stitching together bits from different variants.
There have been multiple recombination events reported in the Covid pandemic. Some previously named lineages include XA, XB and XC.
More recently, a Delta x Omicron recombinant raised some concern, although there hasn’t been a significant surge in infections linked to the variant.
In the case of XE, the variant is a combination of two sub-lineages that emerged from Omicron — BA.1 and BA.2.
In an epidemiological update Wednesday, the the World Health Organisation said that the XE recombinant is being tracked as part of the Omicron variant.
“This recombinant was first detected in the United Kingdom on 19 January and a few hundred sequences have been reported and confirmed since,” WHO said.
Early estimates based on limited preliminary data suggest that XE has a community growth rate advantage of about 10 per cent over BA.2, although this finding requires further confirmation.
The WHO also clarified that some media outlets have misreported the potential growth advantage of 10 per cent as 10 times.
“This is incorrect. If the 10 per cent increase in growth is confirmed, this variant would be 1.1 times more transmissible, not 10 times,” the report said.
The WHO has previously stated that until significant differences in transmission and disease characteristics, such as disease severity, are identified, XE will continue to be categorised as part of the Omicron variant.