The Oxford vaccine appears to protect people against the new, more transmissible variant (B.1.1.7) first found in Britain in end-November and has since become the dominant one in the U.K. The efficacy of the vaccine against the U.K. variant is comparable with the efficacy against other SARS-CoV-2 virus lineages. The results were posted in a preprint server. Preprints are yet to be peer-reviewed and published in scientific journals.

No studies were carried out to examine the efficacy of the vaccine against the variant found in South Africa.

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The vaccine efficacy against primary symptomatic disease caused by the new variant was 74.6% as against 84.1% against symptomatic disease caused by other lineages, the preprint says.

“Data from our trials of the Oxford vaccine in the U.K. indicate that the vaccine not only protects against the original pandemic virus, but also protects against the novel variant,” Andrew Pollard, Professor of Paediatric Infection and Immunity, and Chief Investigator on the Oxford vaccine trial, said in a release.

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Based on blood samples taken from trial participants who had been vaccinated, they found a nine-fold reduction in the neutralising activity levels of the vaccine-generated antibodies against the U.K. variant compared with other lineages.

While neutralising antibody titres generated by vaccination with Oxford vaccine are lower for the new variant, clinical efficacy of the vaccine against symptomatic COVID disease is similar for both the new variant and other lineages. “These findings suggest that either lower neutralising antibody titres are sufficient to provide protection or that other mechanisms of immunity may be responsible for protection from disease in vaccinated individuals,” the preprint says.

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According to the researchers from Oxford University who conducted the study, though there is a reduction in the live neutralising activity of sera from vaccinated people, the “efficacy of the vaccine after a second dose was preserved against the new variant, and is “similar to previously published efficacy results” from cases prior to the emergence of the new variant.

Besides neutralising antibodies, certain antibodies mediating other functions may be recognising and binding to alternative sub-units on the spike protein explaining the observed clinical efficacy against the new variant, they postulate. There is also the likelihood that cellular immune responses to the vaccine have been sustained against the U.K. variant independently of neutralising activity, which might also be playing a role in clinical efficacy of the vaccine against the new variant.

Between October 1, 2020 and January 14, 2021, the researchers used swabs taken from nearly 500 participants with both symptomatic and asymptomatic infection enrolled in a phase-2/3 trial to find out if they were infected with the new variant or other lineages after receiving either the vaccine or the control. Of these, 34 (28.3%) who developed symptoms were infected by the new variant, while 86 (71.7%) were infected by other SARS-CoV-2 lineages. And 14 (32%) asymptomatic infections were due to the new variant and 30 (68%) due to other lineages.