New Delhi: A new study by the scientists of INSACOG (the consortium of laboratories undertaking genome sequencing in India) and the National Centre for Disease Control (NCDC), revealed variants of concern B.1.617.2 and B.1.1.7 were responsible for cases surge in April-May 2021 in Delhi, which marked the beginning of the second wave in the country.
Among its alarming findings of India ‘Delta’ variant, the consortium said the Indian variants– the B.1.617 variant and its lineage B.1.617.2, are primarily responsible for the sudden spike in the Covid-19 infection in Northern India and has a high transmissibility of about 50 per cent, than the Alpha variant found in UK. The Alpha variant (B.1.1.7)was first detected in UK in September 2020.
According to GISAID, UK has identified 249,026 cases of Alpha variant, and 16,038 cases of Delta variant, as of June 3, 2021.
The study however clarified that despite its high virulence, Alpha variant (B.1.1.7) had much higher case fatality ration than ‘Delta’, which is predominant in the Indian region.
Another revelation was on the front of the lineage of Delta variant; according to the study, higher breakthrough risk of B.1.617.2 variant was found as compared to B.1.617. The genomic sequencing of cases sent to GISAID, shows outbreak in Maharashtra was related to B.1.617.1 variant whereas the spike in cases in Punjab was related to the original variant B.1.1.7.
While comparing the viral load of the Alpha and Delta variants, the study found that Delta’s B.1.617.2 variant has a much higher viral load than B.1.1.7.
The study detected strong evolutionary connection between Delhi and Punjab for B.1.1.7 (Alpha) and in Delhi and Maharashtra strong connection was found with B.1.617 (Delta) lineages.
Another important point raised by the study was regarding post-vaccination immunity. “Immunity acquired from natural COVID-19 infection or vaccines is not absolute and reinfections post natural COVID-19 infections, as well as vaccine breakthrough infections, are not uncommon. The recent evidence from the United States suggests vaccine breakthrough infections to be approximately 0.01% in fully vaccinated populations,” the study said.
The study also added that the outbreak in Delhi in April was followed by other states like Kerala, Maharashtra and Punjab. However, no variant of concern was identified in Kerala in January 2021.