South Africa will give the unapproved Johnson & Johnson vaccine to its front-line health workers beginning next week as a study to see what protection it provides from COVID-19, particularly against the variant dominant there, the health minister said Wednesday.Zweli Mkhize said South Africa has scrapped plans to use the Oxford-AstraZeneca vaccine because it “does not prevent mild to moderate disease” of the variant.The one-shot J&J vaccine is still being tested internationally and has not been approved in any country.But Mkhize, in a nationally broadcast address, declared that the vaccine is safe, relying on tests of 44,000 people done in South Africa, the United States and Latin America.