Research by Indian scientists have shown that the Delta Variant of coronavirus is the leading cause for breakthrough infections; that is, infections after vaccination. The study also confirmed earlier findings that this variant, which is the predominant one in India, was more transmissible and increased the rate of infection. It also noted that a single dose of vaccination or having been infected earlier was no protection against this variant. The study by scientists at the CSIR-Institute of Genomics and Integrative Biology and the National Centre of Disease Control has not yet been peer reviewed.
The study analysed 27 instances of breakthrough infection and found the Delta variant to be responsible in 76% of the cases. The scientists have identified a mutation on the Delta variant which, they believe, may have increased its ability to get into human cells. The Delta variant has 12 mutations from the original Sars-Cov-2 virus first seen in Wuhan.
The Delta variant is responsible for the spike in cases in the U.K. too. Studies there have shown that the effectiveness of the Pfizer and Astra Zeneca vaccines are much reduced against this variant — only 33% against symptomatic disease three weeks after the first dose. This correlates with the new Indian study on breakthrough infections. What makes the story important is what it means for India’s vaccination programme. If the ability of the vaccines to prevent serious infection is down to one-third due to the Delta variant, the country has a much longer road ahead in coming out of the pandemic.(The Hindu)
