BHUBANESWAR : Is the highly infectious 'double mutant' that fuelled COVID-19 cases across the country in the second wave this year losing its transmissibility? The genome sequencing of samples in the last week of May in Odisha indicates that the presence of B.1.617 strain has reduced by almost one-third in the State.
The new mutations of the variant were found in only around 40 per cent (pc) samples, down from 60 pc during the first week of May. Of the three lineages of B.1.617, two lineages - B.1.617.1 and B.1.617.2 - have been detected in the State so far.
An analysis of variants revealed the original B1 variant of coronavirus is fast replacing the B.1.617, also known as double mutant. Although the B.1.617 was a mutation of concern across the districts, current data shows it is being replaced by the old variants.
Of the 903 samples sequenced till May 28 in the State, as many as 251 samples carried the B.1.617 lineages including 182 B.1.617.2 and 69 B.1.617.1. Only 30 samples were detected with the UK variant B.1.1.7 till April.
"The share of double-mutant is declining. Around 40 pc of the 173 samples sequenced recently were found to have the twin mutations. The rest are B1 and other variants of less infectivity. The numbers are down in almost every district in Odisha,"said a researcher associated with genome sequencing.
VOC B.1.617 losing transmissibility in State!
Among the neighbouring states, the share of the double mutant in Jharkhand was highest 67.2 pc (of 363 samples), 47.3 pc in Andhra Pradesh (855 samples), 46.7 pc in Telangana (969 samples), 20.3 pc in Chhattisgarh (562 samples) and 27 pc in West Bengal (2,330 samples).
Director of National Centre for Disease Control Dr Sujeet Kumar Singh admitted that the spread of the VOC has been declining over the past couple of weeks. "The reduction in numbers also translates into declining transmissibility, which is a good sign. A majority of the community got exposed due to rapid infection leading to development of antibodies. Once the community has got antibodies, then the infection rate automatically declines," he told The New Indian Express.
Secondly, Dr Singh said immunisation and Covid appropriate behaviour also helped keep the infection rate in control. However, he said the double mutant is still predominant in some states even as the overall number has declined.
The highest 51 samples were found with B.1.617.2 in Angul followed by 36 in Khurda and 26 in Kalahandi, 15 in Puri, 14 in Mayurbhanj, nine in Bhadrak and eight in Jharsuguda. The B.1.617.1 was found in 13 samples in Angul, 11 in Bhubaneswar, eight in Khurda, seven each in Kalahandi and Mayurbhanj.