The vaccines from AstraZeneca and Pfizer/BioNTech may be more effective against the Brazilian variant of coronavirus than previously thought, a new study has found.

The findings, which are not yet peer-reviewed, mean the vaccines may not need to be modified in order to protect against the variant, which is believed to have originated in the Amazonian city of Manaus.

Research from Oxford University measured the level of antibodies that can neutralise – or stop infection from – variants circulating in South Africa, Brazil and elsewhere.

It found that vaccines do not work as well against the variants as against the original strain of coronavirus, but that the P1 Brazilian variant may be less resistant to vaccine-induced antibodies than first feared.

Professor Gavin Screaton, lead scientist on the study, said: “This study extends our understanding of the role of changes in the spike protein in escape from the human immune response, measured as neutralising antibody levels.

“The results suggest that P1 might be less resistant to vaccine and convalescent immune responses than B1351 [South Africa], and similar to B117 [Kent].”

The study used blood samples from people who have natural antibodies generated from a Covid-19 infection, and from those whose antibodies were induced by the Oxford or Pfizer vaccines.

It found a nearly three-fold reduction in the level of virus neutralisation by the antibodies generated by the Oxford and Pfizer vaccines for the Kent and Brazil variants when compared to the original strain, and a nine-fold and 7.6-fold reduction respectively against the South Africa variant.