by BLOOMBERG

The Covid-19 vaccine from AstraZeneca Plc and the University of Oxford was 79% effective in preventing the disease in a U.S. clinical trial, paving the way for the shot’s potential approval.

An independent data safety monitoring board identified no safety concerns, the company said Monday. The shot was also 100% effective at preventing severe disease and death in the first data from a study of more than 30,000 volunteers.

The findings should go some way to bolstering confidence in the product after confusion over its true efficacy and the best dosing regimen has impacted take-up. The vaccine has faced numerous setbacks, most recently over supply issues and possible side effects. A shortfall in deliveries to the European Union has put Astra at odds with the bloc and led officials to oppose exports of the shot from the region as they seek to hold the company to account.

Trials in the U.K. and Brazil last year produced a range of readings due to different dosing amounts and regimens used, and at least 10 EU countries only approved the shot for under-65s initially.

Many have since reversed that decision after more data from real world use showed the vaccine was effective in older people. Older adults made up about a fifth of the tests. Trials last year failed to provide conclusive data for that age group due to a lack of participants over the age of 65.

A number of cases involving serious blood clots found in individuals following their inoculation has also damaged the vaccine’s image. More than a dozen countries suspended use of the shot last week on the reports. The European Medicines Agency and U.K.’s regulator said Thursday that no definitive link could be established between the clots and the vaccine, and the benefits of its use continued to outweigh the risks.