The World Health Organisation (WHO) insisted that the AstraZeneca vaccine was still a vital tool in the global fight against the coronavirus pandemic, after South Africa delayed the start of its inoculation program over concerns about the drug's efficacy against a virus variant.

In South Africa, alarm was raised when a trial at Johannesburg's University of Witwatersrand concluded the AstraZeneca vaccine provided only “minimal” protection against mild to moderate Covid-19 caused by the variant first detected in South Africa.

But Richard Hatchett, head of the Coalition for Epidemic Preparedness Innovations (CEPI), said it was “vastly too early to be dismissing this vaccine”.

“It is absolutely crucial to use the tools that we have as effectively as we possibly can,” he said, speaking at the WHO's regular bi-weekly press briefing on the pandemic.