The Johnson & Johnson logo appears in front of a medical syringe and a vial containing a coronavirus vaccine.
The introduction of a single-dose Johnson & Johnson Covid-19 vaccine is underway in South Africa.
Different levels of effectiveness (how well the vaccine works in a clinical trial) have been reported from these studies in South Africa, the United States, and Brazil, which has caused some confusion about how well the vaccine actually worked.
So what do these numbers really mean?
Subscribe to News24 and you can access our site exclusive journalism and features today.