Existing COVID Vaccines May Protect Against Brazilian Variant: Oxford Study

By Reuters Staff

March 19, 2021

LONDON (Reuters) - Existing vaccines may protect against the Brazilian variant of the coronavirus, according to a University of Oxford study which also highlighted how a variant first found in South Africa poses the biggest headache for vaccine makers.

Coronavirus variants with specific mutations to the spike protein are of concern because scientists worry they will reduce the efficacy of vaccines, as well as immunity gained from prior infection.

The scientists used blood samples from people with antibodies generated by both COVID-19 infection and the Oxford/AstraZeneca and Pfizer/BioNTech vaccines that are being rolled out in Britain.

The data showed a nearly three-fold reduction in the level of virus neutralisation by antibodies generated by the vaccines for the P.1 Brazil variant - similar to the reduction seen with the variant first identified in Kent, Britain, known as B.1.1.7.

"These data suggest that natural- and vaccine-induced antibodies can still neutralise these variants, but at lower levels," it said. "Importantly, the P1 'Brazilian' strain may be less resistant to these antibodies than first feared."

The variant first identified in South Africa triggered a much larger reduction in virus neutralisation, with a 9-fold reduction in Oxford/AstraZeneca's vaccine, and a 7.6-fold reduction for Pfizer/BioNTech.

Last month, South Africa put use of AstraZeneca's shot on hold after data showed it gave minimal protection against mild-to-moderate infection cause by the country's dominant variant.

The authors of the study said that developing vaccines against the South Africa variant, known as B.1.351, should be the "greatest priority for vaccine developers globally".

Andrew Pollard, chief investigator of the Oxford University vaccine trial, said the study provided "new insights that help us be prepared to respond to further challenges to our health from the pandemic virus, if we need to do so".

The study was released ahead of peer review on the bioRxiv preprint server.

"All three variants have mutations in the ACE2 binding site with P.1 and B.1.351 having a virtually identical triplet: E484K, K417N/T and N501Y, which we show confer similar increased affinity for ACE2," the study authors note.

The reason for the differences in neutralization of B.1.351 and P.1 by immune serum are not immediately clear, they conclude, "but presumably reflect the difference in the mutations introduced outside the (receptor binding domain)."

SOURCE: https://bit.ly/3luqyIU bioRxiv, online March 15, 2021.

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