A research study in South Africa further evaluating Johnson & Johnson's Covid-19 vaccine in the field will resume on Wednesday, the health ministry said, after the study was paused over rare cases of blood clots in people given the vaccine.

During the pause, it had been established that there is a one in a million chance of getting a clot after the vaccine, so regulators across the world have recommended the continued use of J&J's shot, the ministry said.

Local regulator SAHPRA, the South African Medical Research Council and health ministry have worked to ensure there is intensified pre-vaccination assessment and post-vaccination monitoring when the J&J study resumes, it added.