LONDON—The vaccine developed by the University of Oxford and AstraZeneca AZN -0.87% PLC is effective against a highly transmissible new variant of the virus that causes Covid-19, according to an analysis that offers further reassurance that a world-wide vaccination drive will help end the pandemic.
Still, the small-scale study showed the vaccine works better against older, more established versions of the virus, which has so far been linked to almost 2.3 million deaths world-wide and more than 100 million cases.
In a study published online Friday, researchers examined blood samples from around 256 participants in a continuing clinical trial of the vaccine who tested positive for Covid-19. The findings are preliminary and haven’t been formally reviewed by other scientists.
Genetic sequencing allowed them to identify which participants were infected with the new variant and who had an older version. A little under a third had the new variant.
The U.K. Coronavirus Variant
By testing antibody levels and other markers of immune-system activity against the virus, the researchers found the vaccine triggered an effective immune response against the new variant in 75% of cases that showed symptoms of infection, and in around two-thirds of cases if those that didn’t show symptoms were also included.
For those with the older strain, the vaccine was effective in 84% of symptomatic cases and 81% of all cases.
The researchers reported sharply differing antibody responses among the two groups, saying antibodies induced by the vaccine were up to nine times less effective at neutralizing the new variant than old. Overall protection was similar, however, suggesting other parts of the immune system are playing a key role, the study said.
“Vaccine efficacy was preserved against the new variant,” the researchers said.
The emergence of more contagious variants of the virus has driven fresh waves of infection in several parts of the world, and stoked concerns the virus might be able to evade vaccines that are now being rolled out across much of the world.
The latest findings from Oxford and AstraZeneca add to signs that, for now, that doesn’t appear to be the case. Pfizer Inc. and Moderna Inc. have reported their vaccines are also effective against new variants, citing similar laboratory tests.
Write to Jason Douglas at [email protected]
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