South Africa hopes to get some doses of Johnson & Johnson's Covid-19 vaccine around the end of this week, a senior health official said on Monday, after halting use of the AstraZeneca vaccine due to disappointing trial data.

Johnson & Johnson's (J&J) vaccine was a good fit at this stage, health ministry Deputy Director-General Anban Pillay told state broadcaster SABC, but did not say how many doses the country would soon receive.

Previously, South African President Cyril Ramaphosa said the country had secured 9-million J&J doses that were due to start arriving in the second quarter.

The J&J vaccine is not yet authorised for use in South Africa, although the US company has initiated a "rolling submission" with local regulator SAHPRA.

Pillay said the J&J vaccine had shown in trials to be highly effective in preventing hospitalisation and death, and said it was an advantage that it was a one-shot vaccine that could be stored at fridge temperatures.

"So we think it will be a good vaccine at this point in time for South Africa," he said.

On Sunday, the government said it was temporarily halting a large-scale rollout of AstraZeneca's vaccine to healthcare workers after preliminary data from a clinical trial found it gave "minimal protection" against mild-to-moderate infection caused by the dominant 501Y.V2 coronavirus variant in South Africa.

The trial did not assess the vaccine's efficacy against severe infection, and its findings have not yet been peer-reviewed.

AstraZeneca, which developed the vaccine with Oxford University, says it believes its vaccine can protect against severe disease and has already started adapting it against the 501Y.V2 variant.

Asked whether the sample size of the AstraZeneca trial was large enough to draw conclusions from, Pillay said: "I don't think we can be confident to say the vaccine doesn't work, but we also don't have the data to say it certainly will work. What we have are potential indicators."

He said the government needed a "broader discussion" with local and global scientists to interpret the trial data and say what the best way forward would be.

South Africa - which has reported the highest number of confirmed coronavirus infections in Africa and over 46 000 coronavirus-related deaths - hopes to vaccinate 40-million people, or two-thirds of the population, to achieve some level of herd immunity.