A coronavirus variant first detected in Brazil poses less of a threat to vaccines developed by AstraZeneca and Pfizer than researchers first worried, according to new findings announced Thursday by Oxford University.
"The results suggest that P1 [the Brazil variant] might be less resistant to vaccine and convalescent immune responses than B1351, and similar to B117," Professor Gavin Screaton, lead scientist on the study, said in part in a release posted Thursday by Oxford University.
A large team of researchers affiliated with Oxford University posted the findings this week ahead of peer review in the bioRxiv server. Oxford University developed one of the vaccines under study in collaboration with AstraZeneca, which sent several mostly European countries reeling in the last week, ordering temporary suspensions of AstraZeneca vaccinations amid blood clotting reports. Europe’s regulator, the European Medicines Agency, convened a safety committee Thursday to discuss the data and plans to communicate any action taken if deemed necessary.
In the preliminary study at hand, researchers noted the Brazil (P.1), South Africa (B.1.351) and U.K. variants share mutations at the virus’s binding site, and suggested mutations located elsewhere could account for the differing impacts on neutralization power.
"We show that, surprisingly, P.1 is significantly less resistant to naturally acquired or vaccine induced antibody responses than B.1.351 suggesting that changes outside the RBD [receptor binding domain] impact neutralisation," study authors wrote.
Researchers looked at over 30 blood samples from previously infected individuals and 50 other blood samples from those vaccinated with either the Pfizer or AstraZeneca vaccines.
Results indicated the Brazil and U.K. strains had a similar approximate three-fold reduction in neutralization power for the Pfizer and AstraZeneca vaccines. The South African variant, by comparison, had a much greater impact, resulting in a 7.6-fold, and 9-fold reduction in Pfizer and AstraZeneca vaccine neutralization power, respectively.
As far as naturally-derived protection from prior infection, the Brazil and U.K. strains resulted again in a similar approximate three-fold reduction, compared to a 13.3-fold drop inflicted by the South African variant.
"These data suggest that natural- and vaccine-induced antibodies can still neutralise these variants, but at lower levels," per the release.
Separate studies have previously suggested the South African variant dropped the Pfizer vaccine's neutralization power by about two-thirds, while Moderna saw a six-fold reduction in neutralizing antibodies.
"These further efforts to investigate the relationship between changes in the virus and human immunity provide 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," Professor Andrew Pollard, chief investigator on the Oxford University vaccine trial, said in the release.