BioNTech/Pfizer vaccine is less potent against South African variant

The BioNTech/Pfizer Covid-19 vaccine appears to be significantly less effective against the virus variant that emerged in South Africa, according to a study published on Wednesday. 

The vaccine still works against the strain known as 501Y.V2, but the shot produced only a third of the antibodies that it did for the original virus in a lab study using an engineered virus. 

The partners said there was “no clinical evidence” that people vaccinated with their Covid-19 shot lacked protection against the variant. It is hard to draw firm conclusions from lab experiments on how the vaccines will work on the variants in humans. 

But they said they were making investments and talking to regulators so they could seek authorisation for an updated vaccine or a booster shot “once a strain that significantly reduces protection from the vaccine is identified”. 

The vaccine from BioNTech/Pfizer was the first to receive emergency approval in many countries, including the US and the UK. The pair expect to make up to 2bn doses this year.

The paper, published in The New England Journal of Medicine, is based on experiments using the blood of 20 vaccine trial participants. The scientists from Pfizer, BioNTech and the University of Texas Medical Branch tested three different genetically engineered viruses, one with all the mutations of 501Y.V2, and two with subsets of the changes. 

The scientists had previously found that the vaccine was likely to be effective against B.1.1.7, which first emerged in the UK.

But many other vaccine makers have found their shots are far less effective against the South African variant. South Africa halted the rollout of the Oxford/AstraZeneca vaccine after preliminary data showed it failed to protect against mild and moderate forms of Covid-19 caused by the new strain. 

In clinical trials with sites in South Africa, both Johnson & Johnson and Novavax found their vaccines were less effective against the variant. In a lab study, Moderna found its vaccine only produced one-sixth of the antibodies in response to the 501Y.V2 variant than it did to the original virus. 

Some vaccine makers, including Novavax and Moderna, are already preparing for clinical trials of a reformulated vaccine or a booster shot. 

BioNTech/Pfizer’s vaccine — like Moderna’s — is based on messengerRNA technology that can be quickly adapted to new variants. The companies said they were evaluating the vaccine against other strains, including one that first emerged in Brazil, and were conducting studies to monitor the vaccine’s effectiveness outside of the laboratory. 

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