Updated: May 7, 2021 7:27:35 am
The genome sequencing of the Covid 19 virus in circulation in Karnataka in the second wave since March has revealed that the double mutant Maharashtra strain (B.1.617) and UK variant (B.1.1.7) have virtually obliterated the previous strain dominant in the state (B.1.36.29).
This has been revealed in a study by the Department of Virology at Nimhans — one of the 10 labs in the country carrying out genome sequencing of coronavirus strains. “The rapid displacement of B.1.36.29 by the UK and Maharashtra variants is suggestive of higher infectivity. The higher infectivity of the UK variant is known but it has to be established for B.1.617,” said Prof V Ravi, former head of neurovirology at Nimhans who is working on Covid 19 genomics at the lab.
However, the virologist added, there was no evidence yet to indicate that any strain is more severe than the other. “In terms of clinical behaviour, the virus is the same. We are seeing more severe cases because we are seeing five times the number of cases seen earlier. The severity has nothing to do with mutants. There is absolutely no evidence,” Ravi said.
The Nimhans study, which is yet to be published, found the B.1.617 strain in 36 of the 69 (52%) positive samples collected between March and end-April, and B.1.1.7 in 19 of them (27.5%). In contrast, the study says, from December 2020 to early March 2021, the dominant variant in Karnataka was B.1.36.29, which has been in circulation since March 2020
“In Delhi and Punjab the UK variant is a problem and in Maharashtra and 16 other states the B.1.617 double mutant has become a problem,” Ravi said, adding there are “about 34 different lineages” in circulation and stressing the need to increase the sample size and scope of the genome study.
According to the Nimhans study, which was shared by Ravi during a recent talk, the UK variant and the Maharashtra double mutant were in community transmission in Bengaluru by the end of March; “50 per cent of sequences in south Bengaluru in the last week of March (were) the Maharashtra variant”, it said.
Karnataka is seeing a Covid-19 surge since end March. On May 5, it saw over 50,000 cases and 346 deaths, with Bengaluru accounting for nearly half of each. From outside the capital, 185 deaths were recorded — the highest in the second wave.
The previously dominant strain in Karnataka, B.1.36.29 emerged during the lockdown last year. By end February 2021, it was prevalent in 20-30% of cases, as per the Nimhans study.
Ravi said the second wave would affect all the states and a third wave would come later in the year. “My prediction is that it will be between October and December. We are in it for the long haul unless we change our behaviour and unless our leaders change their behaviour… All variants or no variants do not make a difference if you wear masks. They do not penetrate masks.”
The scientist cautioned that children could be hit the worst in the third wave. “We are immunising the elderly, middle aged and the young but there is no vaccine for children. The virus will always find a susceptible host,” Ravi said, adding that he has been advising the government to set up paediatric ICUs.
An earlier Nimhans study on the molecular profiles of the SARS Cov-2 virus circulating in Karnataka in March-May 2020 was published in PLOS One — a peer-reviewed open access scientific journal. The study was unique in its use of genome data and epidemiological information to assess the nature of the virus responsible for the early spread.
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