The Covid-19 virus that is doing the rounds in Bengal is increasingly being found to be an indigenous triple-mutation (B.1.618), only the second one identified from India after the double mutant type (B.1.617) reported last month, reports Subhro Niyogi. The Covid-19 virus that is doing the rounds in Bengal is increasingly being found to be an indigenous triple-mutation (B.1.618), only the second one identified from India after the double mutant type (B.1.617) reported last month, reports Subhro Niyogi.