Jahnavi Sarma
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Written By: Jahnavi Sarma | Updated : August 19, 2021 12:18 PM IST
Today, the Delta variant of COVID-19 has become the dominant virus variant and it has caused a significant surge in infections in many countries. This has resulted in thousands of hospitalisations and deaths. In this scenario, the first thing that comes to mind is how effective are the COVID-19 vaccines against this virulent variant? According to a new study published in the journal Immunity, the Delta variant of COVID-19 is not particularly good at evading the antibodies generated by the Pfizer vaccine. This explains why vaccinated people have largely escaped the worst of the Delta surge.
For the purpose of the study, researchers from Washington University's School of Medicine in St. Louis in the US extracted antibody-producing cells from three people who had received the Pfizer vaccine. They grew the cells in the laboratory and obtained from them a set of 13 antibodies that target the original strain that began circulating last year. Then they tested the antibodies against four variants of concern: alpha, beta, gamma and delta. Twelve of the 13 recognised alpha and delta, eight recognised all four variants, and one failed to recognise any of the four variants. Five of the 13 antibodies neutralised the original strain. When the team tested the neutralising antibodies against the new variants, all five antibodies neutralised the delta variant, three neutralised alpha and delta, and only one neutralised all four variants.
The antibody that neutralised all four variants of concern was called 2C08. In animal experiments, researchers earlier saw that this antibody 2C08 also protected hamsters from disease caused by every variant tested: the original variant, delta and a mimic of beta. According to researchers, some people may have antibodies that are just as powerful as 2C08, which provides them protection against COVID-19 and its many variants. Using publicly available databases, the researchers found that around 20 per cent of people who were infected or vaccinated against SARS-CoV-2 create antibodies that recognise the same spot on the virus that is targeted by 2C08. Moreover, very few virus variants (.008 per cent) carry mutations that allow them to escape antibodies targeting that spot.
According to the researchers of this study, the ability of a variant to spread is the sum of many factors. Resistance to antibodies is just one of those factors. Another one is how well the variant replicates. A variant that replicates better is also likely to spread faster, independent of its ability to evade the immune response of the host. So, there is a surge in Delta variant cases, yes, but there's no evidence that it is better at overcoming vaccine-induced immunity as compared to other variants.
(With inputs from IANS)
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