Oxford vaccine ‘significantly less effective against South Africa variant’, study suggests

The findings were based on early phase I and II trials

Credit: EPA

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AstraZeneca says its vaccine developed with the University of Oxford appeared to offer only limited protection against mild disease caused by the South African variant of Covid-19, based on early data from a trial.

The study from South Africa’s University of the Witwatersrand and Oxford University showed the vaccine had significantly reduced efficacy against the South African variant, according to a Financial Times report.

Among coronavirus variants currently most concerning for scientists and public health experts are the Kent, South African and Brazilian variants, which appear to spread more swiftly than others.

"In this small phase I/II trial, early data has shown limited efficacy against mild disease primarily due to the B.1.351 South African variant," an AstraZeneca spokesman said in response to the FT report.

The newspaper said none of the more than 2,000 trial participants had been hospitalised or died.

"However, we have not been able to properly ascertain its effect against severe disease and hospitalisation given that subjects were predominantly young healthy adults," the AstraZeneca spokesman said.

Read more: The Oxford, Pfizer and other vaccines compared

The company said it believed its vaccine could protect against severe disease, given that the neutralising antibody activity was equivalent to that of other Covid-19 vaccines that have demonstrated protection against severe disease.

The trial, which involved 2,026 people of whom half formed the placebo group, has not been peer-reviewed, the FT said.

While thousands of individual changes have arisen as the virus mutates into new variants, only a tiny minority are likely to be important or change the virus in an appreciable way, according to the British Medical Journal.

"Oxford University and AstraZeneca have started adapting the vaccine against this variant and will advance rapidly through clinical development so that it is ready for autumn delivery should it be needed," the AstraZeneca spokesman said.

On Friday Oxford said their vaccine has similar efficacy against the British coronavirus variant as it does to the previously circulating variants.