How Pfizer Covid vax cuts risk of Delta infection

New York, Aug 18 (IANS): Despite causing a surge in infections that has resulted in thousands of hospitalisations and deaths, the Delta variant of Covid-19 is not particularly good at evading the antibodies generated by the Pfizer vaccine, according to a study.

The findings, published in the journal Immunity, help explain why vaccinated people have largely escaped the worst of the delta surge.

Researchers at Washington University 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.

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.

Five of the 13 antibodies neutralised the original strain. When the team 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.

"The fact that delta has outcompeted other variants does not mean that it's more resistant to our antibodies compared to other variants," said Jacco Boon, Associate Professor of medicine, of molecular microbiology and of pathology and immunology at the University's School of Medicine in St. Louis.

The antibody that neutralised all four variants of concern -- as well as three additional variants tested separately -- was called 2C08. In animal experiments, 2C08 also protected hamsters from disease caused by every variant tested: the original variant, delta and a mimic of beta.

Some people may have antibodies just as powerful as 2C08 protecting them against SARS-CoV-2 and its many variants, said Ali Ellebedy, Associate Professor of pathology and immunology, of medicine and of molecular microbiology, at the varsity.

Using publicly available databases, the researchers discovered that about 20 per cent of people 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.

"The ability of a variant to spread is the sum of many factors. Resistance to antibodies is just one factor. Another one is how well the variant replicates. 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," Boon said.



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Comment on this article

  • Rudolf Rodrigues, Mumbai

    Thu, Aug 19 2021

    Mumbai reported the first death from the Delta Plus variant of the coronavirus, a 63-year-old woman who was fully vaccinated, researchers have expressed concern about breakthrough infections spreading the virus to others. Reports suggest that the Delta variant, which led to the second wave Covid-19 in India, is more likely to spread through vaccinated people than other variants. Reports from the US and the UK have indicated that people infected with the Delta variant of SARS CoV-2 can carry as much viral load as unvaccinated people. Researchers studied PCR tests, which detect the virus’ genetic material by amplifying DNA, and threshold cycle (Ct) data to analyse the situation after a new surge in cases owing to the Delta variant. A study published in medRxiv preprint, which is yet to be peer-reviewed, states that "individuals had similar viral loads in nasal swabs, irrespective of vaccine status, during a time of high and increasing prevalence of the Delta variant". The new findings stress the importance of protective measures, including the wearing of masks indoors to reduce transmission, even among vaccinated groups

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  • John, Mangalore

    Wed, Aug 18 2021

    But CDC says Fully Vaccinated Spreading Delta Variant? Also CDC to Withdraw Emergency Use Authorization for RT PCR Test Because It Cannot Distinguish Between SARS-CoV-2 and the Flu... more on it at and More CDC Insanity: Fully Vaccinated Spreading Delta Variant – So Everyone Needs to Get Vaccinated and Wear Masks.... more on it at

    DisAgree Agree [1] Reply Report Abuse

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