Johnson & Johnson announced Friday that its coronavirus vaccine was 66 percent effective against the infectious disease. Perhaps most crucially, while the jab joined the rest of the vaccine pack in appearing to be less impactful against a surging virus variant in South Africa, it was still 57 percent effective among trial participants there, the company said. The first cases of that variant in the United States were identified in South Carolina this week.

The pharmaceutical and consumer goods giant says its preventative offers protection after just one dose, in contrast with the first-to-market Moderna and Pfizer vaccines, which are both 90 percent effective against (at least earlier variants of) the virus but require two injections a month apart. In its announcement, J&J said its one-shot vaccine was 85 percent effective at preventing severe disease, and offers “complete protection” from hospitalization and death from COVID-19.