A healthcare professional will prepare a dose of the Oxford / AstraZeneca Covid-19 vaccine at the vaccine center at the Brighton Center in Brighton, southern England on January 26, 2021.

Ben Stensall | AFP | Getty Images

LONDON – The results of a large US study showed that the coronavirus vaccine developed by AstraZeneca and the University of Oxford is 79% effective in preventing symptomatic illness and 100% effective against serious illness and hospitalization.

The vaccine’s safety and efficacy analysis published on Monday was based on 32,449 participants from a Phase 3 study.

It comes shortly after a spate of countries temporarily suspended the use of the shot after reports of blood clots in some vaccinated people. Health experts sharply criticized the move, citing a lack of data, while analysts expressed concerns about the impact on vaccine uptake as the virus continues to spread.

Germany, France, Italy and Spain, among others, have resumed use of the Oxford-AstraZeneca vaccine after the European Medicines Agency found the shot was both safe and effective in its initial investigation into possible side effects.

AstraZeneca said an independent board had not identified any safety concerns related to the shot. With the help of an independent neurologist, they also performed a specific check for blood clots as well as cerebral venous sinus thrombosis, an extremely rare blood clot in the brain.

The Data Safety Monitoring Board “found no increased risk of thrombosis or events characterized by thrombosis in the 21,583 participants who received at least one vaccine dose. The specific search for CVST found no events in this study.”

Ann Falsey, Professor of Medicine in the School of Medicine at the University of Rochester, USA, and Co-Lead Principal Investigator for the study, said, “This analysis validates the AstraZeneca COVID-19 vaccine as a much-needed additional vaccine option and offers adults confidence all ages can benefit from protection against the virus. “