AstraZeneca vaccine 79% effective in US, shows no safety issues

AstraZeneca Plc’s coronavirus vaccine fared better than expected in a U.S. clinical trial, providing reassurance about its safety and efficacy.

The shot developed with the University of Oxford was 79% effective in preventing COVID-19, and an independent monitoring board found no safety concerns, the company said Monday. The shot also protected all those immunized from severe disease and death in a study of more than 30,000 volunteers.

The findings should bolster confidence in the product after confusion over its true efficacy and the best dosing regimen impacted take-up. The vaccine has faced numerous setbacks, most recently over supply issues and possible side effects. Even after the European Medicines Agency declared it safe last Thursday, not all European Union countries have resumed vaccination on concern about reports of blood clots.

“Efficacy is better than we had expected,” Peter Welford, an analyst at Jefferies, wrote in a note to clients. “Importantly, after recent largely unfounded safety concerns in Europe, the study confirms the safety profile.”

Astra shares rose as much as 1.2% in London trading.

A shortfall in deliveries to the EU 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.

Clinical 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 for everyone. Older adults made up about a fifth of the U.S. test, which showed efficacy of 80% in that age group. Trials last year failed to provide conclusive data 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. The U.S. trial review that found no safety concerns looked specifically at blood clots.

Skepticism over the vaccine started last year. When Astra and Oxford first reported initial data from clinical trials conducted in the U.K. and Brazil last November, they produced two very different efficacy readings of 62% and 90%. Because of a manufacturing error, one group of participants had received a lower first dose, which produced the higher reading, compared with those getting two standard doses. Further analysis suggested it was the dosing gap rather than the amount that had created the difference.

More than 70 countries globally have approved the Astra-Oxford shot for use and the partners plan to produce up to three billion doses of the vaccine this year.

The vaccine is particularly important to the global effort to end the pandemic because it’s easy to store and transport and the company is providing it at no profit during the crisis. Unlike vaccines from Pfizer Inc. and partner BioNTech SE, and Moderna Inc., which have to be kept frozen, the Astra shot can be held at fridge temperature. — Bloomberg