Karim also said the AstraZeneca vaccine would in future be rolled out in a "stepped manner" to assess its ability to prevent severe illness.
The country, which has recorded the most coronavirus infections in Africa and more than 46,000 deaths, had planned to start offering healthcare workers the AstraZeneca jabs soon but put that plan on hold on Sunday.
A government factsheet published on Monday said the J&J vaccine would be offered from mid-February. A senior health official said J&J had agreed to speed up deliveries so the first doses would become available around the end of the week.
Preliminary trial data showing the AstraZeneca shot does not significantly reduce the risk of mild-to-moderate illness caused by the more contagious 501Y.V2 variant first identified late last year was a disappointment not just to South Africa, but to the continent as a whole.
The 501Y.V2 variant is believed to have spread to nine other African countries, according to a World Health Organization (WHO) epidemiological report last week.
The AstraZeneca vaccine is seen as one of the best suited to weak African health systems as it can be stored at refrigerator temperatures, rather than the ultra-cold temperatures needed for shots from Pfizer/BioNTech.
- That study, which looked at only mild and moderate infections raised concerns, not because that we were not expecting some diminishing activity. But it was the level to which it was diminished. And so now we are unclear and uncertain about the efficacy of the vaccine to preventing hospitalization and severe disease. We know from the overall trial that the AstraZeneca vaccine is effective against other pre-existing variants. We're just not confident about its efficacy against the 501Y.V2 variant.
We don't want to end up with a situation where we have vaccinated 1 million people or 2 million people with a vaccine that may not be effective in preventing hospitalization and severe disease.
We've proposed an alternative approach, a new approach to the way in which to roll out the vaccine. And one proposal that's currently being considered is to roll it out, initially, just in a stepped manner, where the first step includes about 100,000 individuals that are vaccinated in which we monitor the hospitalization rates. If they are below the threshold that we are looking for, then we are confident that the vaccine is effective, again, in preventing hospitalization. And then we can roll it out. Alternatively, if it's above that threshold, then we need to look at alternatives.
We were scheduled to roll out the AstraZeneca vaccine in just over a week from now. We anticipate that the initial start date of vaccinations will be largely unaffected or at most affected by a few days. But instead of rolling out AstraZeneca vaccine, we'll be rolling out the Johnson & Johnson vaccine.