- Early data from the study appears to show that be less effective against the variant first found in South Africa, in those with mild disease
- The study has not yet been peer-reviewed, and trial subjects were predominantly young, healthy adults
- AstraZeneca says it has started adapting the vaccine against the variant
British drugmaker AstraZeneca said on Saturday its vaccine developed with the University of Oxford appeared to offer only limited protection against mild disease caused by the variant of Covid-19 discovered in South Africa, based on early data from a trial.
The study from the University of the Witwatersrand and Oxford University showed the vaccine had significantly reduced efficacy against the variant detected in South Africa, according to a Financial Times report published earlier in the day.
Among coronavirus variants currently most concerning for scientists and public health experts are the so-called British, 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 spokesperson 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 spokesperson said.
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The trial, which involved 2 026 people of whom half formed the placebo group, has not been peer-reviewed, the FT said.
According to the BBC, the study is due to be published on Monday.
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 spokesperson said.
On Friday Oxford said their vaccine has similar efficacy against the coronavirus variant discovered in the UK as it does to the previously circulating variants.