AstraZeneca’s US clinical trial of its Covid-19 vaccine developed with Oxford university has shown 79 per cent efficacy at preventing symptomatic disease and 100 per cent efficacy against severe or critical disease and hospitalisation.
A fifth of the participants in the trial were over the age of 65 and the jab showed 80 per cent efficacy in these older participants, the long-awaited results showed on Monday.
The AstraZeneca vaccine is currently embroiled in a safety row in Europe, with some countries pausing its rollout after registering a series of rare side events involving a specific type of blood clot.
The European regulator, the European Medicines Agency, has said throughout the safety crisis that the vaccine’s benefits far outweigh its risks, but some countries have opted to halt the rollout, pending more data.
Crucially, the US trial found the vaccine was well tolerated, AstraZeneca said, and the independent data safety monitoring board identified no safety concerns related to the vaccine.
In particular the group reviewed the “thrombotic events”, including cerebral venous sinus thrombosis, which have caused concern across Europe, with the assistance of an independent neurologist.
The monitoring board found no increased risk of thrombosis or events characterised by thrombosis among the 21,583 participants receiving at least one dose of the vaccine. The specific search for CVST found no cases in this trial.
This US trial involved 32,449 people, including 141 symptomatic cases of Covid-19.
Ann Falsey, professor of medicine at the University of Rochester and a principal investigator for the trial, said: “These findings reconfirm previous results observed in [earlier] trials across all adult populations but it’s exciting to see similar efficacy results in people over 65 for the first time.
“This analysis validates the AstraZeneca Covid-19 vaccine as a much-needed additional vaccination option, offering confidence that adults of all ages can benefit from protection against the virus.”
Mene Pangalos, executive vice-president of Biopharmaceuticals R&D at AstraZeneca, said: “These results add to the growing body of evidence that shows this vaccine is well tolerated and highly effective against all severities of COVID-19 and across all age groups.
“We are preparing to submit these findings to the US Food and Drug Administration and for the rollout of millions of doses across America should the vaccine be granted US emergency use authorisation.”