South Africa on Sunday suspended plans to inoculate its front-line health care workers with the Oxford-AstraZeneca vaccine, after a small clinical trial suggested that it isn't effective in preventing mild to moderate illness from the variant dominant in the country, The Associated Press reports.

South Africa got its first 1 million doses of the AstraZeneca vaccine last week and was expected to begin giving shots to health care workers in mid-February.

On Saturday, the British drugmaker said the vaccine appeared to offer only limited protection against mild disease caused by the South African variant of COVID-19.

A study from South Africa's University of the Witwatersrand and Oxford University showed the vaccine had significantly reduced efficacy against the South African variant.

South African Health Minister Zweli Mkhize said Sunday night, "The AstraZeneca vaccine appeared effective against the original strain but not against the variant. We have decided to put a temporary hold on the rollout of the vaccine. ... More work needs to be done."

Scientists will study whether the AstraZeneca vaccine works against the variant to prevent death and severe disease, Mkhize said, according to AP.

An Oxford University professor said last week that a vaccine against the coronavirus' new mutations should be ready by October.

According to the university's Professor Andrew Pollard, who heads the team working on the vaccine, tweaking the vaccine is a relatively fast process and needs only small trials before the vaccine can be rolled out.

Though studies show that existing vaccines provide some protection against the South African mutation of COVID-19, they have also showed reduced efficacy against it.