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The Covid-19 vaccine from AstraZeneca Plc has shown limited effectiveness against mild disease caused by the variant first identified in South Africa, according to initial data from a small-phase trial.
The effectiveness against serious cases of Covid-19, hospitalization and deaths has yet to be determined, “given that the subjects were predominantly healthy young adults,” an AstraZeneca spokesman said in a statement.
None of the study participants died or was hospitalized, according to the Financial Times, which first reported on the study’s findings. The study, with a relatively small sample of more than 2,000 individuals, has not yet been peer-reviewed and is due to be published on Monday, the newspaper said. The patients in the randomized double-blind study had a median age of 31 years.
“We believe that our vaccine can protect against serious diseases, as the activity of neutralizing antibodies is equivalent to that of other Covid-19 vaccines that have shown activity against more serious diseases, particularly when the dosage interval is optimized for 8-12 weeks,” Said the AstraZeneca spokesman.
Initial data indicate that other immune responses, such as T cell responses, may remain intact in the South African variant, the spokesman added.
The variant first identified in South Africa is emerging as a key threat to the world’s prospects for ending the pandemic, as countries implement initial doses of the vaccine. Although vaccine manufacturers have said that their vaccines appear to maintain effectiveness against UK variants, pharmaceutical companies are rushing to develop booster shots against new variants as the virus evolves.
Oxford University and AstraZeneca have started adapting their vaccine against this variant, the spokesman said. If necessary, they will advance clinical development so that they are ready for delivery in the fall.
Earlier this week, Astra’s executive vice president for biopharmaceutical research lowered expectations of how the vaccine would work against the variant.
“We will not be surprised to see reduced effectiveness,” said Mene Pangalos. “It is to be expected that there will be a reduction in activity.”
(Updates with AstraZeneca’s statement starting in the second paragraph.)