Why vaccinated people have largely escaped the worst of the Delta surge
2 min read . Updated: 18 Aug 2021, 04:06 PM IST
Premium- Analysis of a panel of antibodies generated by people in response to the Pfizer COVID jab found that Delta was unable to evade all but one of the antibodies they tested
- Other variants of concern, such as Beta, avoided recognition and neutralisation by several of the antibodies
The Delta variant of coronavirus is unable to evade the antibodies generated by vaccination, said a study published in the journal Immunity. The study further explains why vaccinated people have largely escaped the worst of the Delta surge.
Analysis of a panel of antibodies generated by people in response to the Pfizer COVID-19 jab found that Delta was unable to evade all but one of the antibodies they tested, researchers at Washington University School of Medicine said.
Other variants of concern, such as Beta, avoided recognition and neutralisation by several of the antibodies, the researchers also said.
In other studies, Ali Ellebedy, an associate professor at the varsity, had shown that both natural infection and vaccination elicit lasting antibody production. However, the researchers noted that the length of the antibody response is only one aspect of protection, and breadth matters too.
Researchers said, an ideal antibody response includes a diverse set of antibodies with the flexibility to recognise many slightly different variants of the virus.
They also said, breadth confers resilience, adding that even if a few antibodies lose the ability to recognise a new variant, other antibodies in the arsenal should remain capable of neutralising it.
However, Jacco Boon, an associate professor at Washington University, points out just because Delta has outcompeted other variants does not mean that it's more resistant to our antibodies compared to other variants.
He adds, "A variant that replicates better is likely to spread faster, independent of its ability to evade our immune response. So Delta is surging, yes, but there's no evidence that it is better at overcoming vaccine-induced immunity compared to other variants."
How tests were conducted to asses the breadth of the antibody response
In order to assess the breadth of the antibody response to coronavirus, the scientists extracted antibody-producing cells from three people who got Pfizer vaccine. The cells were then grown at the lab and later, a set of 13 antibodies were obtained from them that target the original strain which began circulating last year. The researchers 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.
Scientists gauge an antibody's usefulness by its ability to block virus from infecting and killing cells in a dish.
The neutralising antibodies that prevent infection are thought to be more powerful than those that recognise the virus but can't block infection, although both neutralising and non-neutralising antibodies contribute to defending the body.
The researchers found that five of the 13 antibodies neutralised the original strain.
When they tested the neutralising antibodies against the new variants, all five antibodies neutralised Delta, three neutralised Alpha and Delta, and only one neutralised all four variants.
"In face of vaccination, Delta is relatively a wimpy virus. If we had a variant that was more resistant like Beta but spread as easily as Delta, we would be in more trouble," Ellebedy said.
The antibody that neutralised all four variants of concern -- as well as three additional variants tested separately -- was called 2C08, the researchers said.
(With inputs from agencies)
