AstraZeneca’s Covid-19 Vaccine Is Found to Be 79% Effective in U.S. Study

The coronavirus vaccine developed by AstraZeneca and the University of Oxford provided strong protection against Covid-19 in a large clinical trial in the United States, completely preventing the worst outcomes from the disease while causing no serious side effects, according to results announced on Monday.

The findings, announced in a news release from AstraZeneca, may help shore up global confidence in the vaccine, which was shaken this month when more than a dozen countries, mostly in Europe, temporarily suspended the shot’s use over concerns about possible rare side effects.

The trial, involving more than 32,000 participants, was the largest test of its kind for the shot. The vaccine was 79 percent effective overall in preventing symptomatic infections, higher than observed in previous clinical trials. The trial also showed that the vaccine offered strong protection for older people, who had not been as well-represented in earlier studies.

But the fresh data may not make much difference in the United States, where the vaccine is not yet authorized.

If AstraZeneca’s vaccine is authorized for use in the United States, it is unlikely to become available before May, when federal officials predict that there will be enough vaccine doses for all the nation’s adults from the three manufacturers that already have authorization.