Health workers will start getting their COVID-19 vaccine booster shots in the second Sisonke trial that gets under way on Monday.
The rest of the general public who got the Johnson & Johnson treatment will eventually also get boosters.
Unlike the first trial, healthcare workers will be able to get their booster shots at allocated private vaccine sites and won’t have to wait in long queues at selected public health venues.
Almost half a million people were vaccinated as part of the study, which opened the country’s inoculation programme.
The Health Department said that there were some healthcare workers who would prefer to hold on and wait for the clearance of a Pfizer booster shot but it was not clear when that would be.
The Johnson & Johnson booster shot is still part of the study as experts want to use the outcome of the study to determine how long the first shot lasts and at what point a booster shot is needed for the general public.
Those eligible to participate in the study will receive information via SMS before they can register on the Electronic Vaccination Data System (EVDS) portal.