JOHANNESBURG—South Africa started administering Johnson & Johnson ’s Covid-19 vaccine, which has yet to be authorized anywhere, to healthcare workers, as the country grapples with a new, more contagious coronavirus strain.
The South African government scrambled to secure the J&J shots after halting a planned rollout of a vaccine developed by AstraZeneca and the University of Oxford earlier this month. That followed results from a small clinical trial in South Africa that found the AstraZeneca vaccine didn’t appear to protect recipients from developing mild or moderate illness from the fast-spreading new strain of the coronavirus first detected in the country.
The J&J vaccine was found to be 57% effective at preventing moderate and severe Covid-19 symptoms in a larger trial held in South Africa, including from the B.1.351 variant, which has become the predominant version there. That was lower than the 72% efficacy rate observed during J&J’s trial in the U.K., which vaccine experts attributed to the South African variant’s ability to partially escape the immune response triggered by some Covid-19 vaccines.
When looking at just severe Covid-19 cases, the J&J vaccine was found to be 85% effective, including in South Africa.
