AstraZeneca’s US clinical trial on its Covid-19 vaccine developed with the University of Oxford has shown an efficacy of 79% in preventing symptomatic illnesses and 100% against serious or critical illnesses and hospitalization.
A fifth of the trial participants were over 65 and the jab showed 80% effectiveness in these older participants, the long-awaited results showed on Monday.
The AstraZeneca vaccine is currently involved in a safety line in Europe, with at least 16 countries halting or limiting its deployment after recording a series of rare side events involving a specific type of blood clot.
The European Medicines Agency has said the vaccine’s benefits far outweigh its risks, but some countries have chosen to continue to halt the deployment, pending more data. An EMA probe last week found no connection to general blood clotting, but left the door open to the possibility of a link with a rare combination of events that include blood clots in the brain, low platelet count and bleeding.
Essentially, the US trial found the vaccine to be well tolerated, AstraZeneca said, and the independent data safety oversight committee did not identify any safety issues with the vaccine.
In particular, the group reviewed ‘thrombotic events’, including cerebral venous sinus thrombosis, which have caused concern across Europe, with the help of an independent neurologist.
The Supervisory Board found no increased risk of thrombosis or events characterized by thrombosis among the 21,583 participants receiving at least one dose of the vaccine. Specific search for CVST did not find any cases in this trial.
The vaccine, easy to store and transport and currently sold at cost, is also at the center of a diplomatic row between the EU and the UK, with the ancient threatening to block exports of jabs, including doses of AstraZeneca, to the latter.
The American trial of AstraZeneca involved 32,449 people, including 141 symptomatic cases of Covid-19. The drugmaker’s London-listed shares gained at least 1.1% shortly after the opening.
Ann Falsey, professor of medicine at the University of Rochester and principal investigator of the trial, said: “These results confirm the earlier results seen in [earlier] trials in all adult populations, but it is 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 supplemental vaccination option, providing confidence that adults of all ages can benefit from protection against the virus,” she said.
Mene Pangalos, executive vice president of biopharmaceuticals R&D at AstraZeneca, said the company was preparing to submit the results to the U.S. Food and Drug Administration for approval.
Vaccines made by BioNTech / Pfizer, Moderna and Johnson & Johnson have shown varying degrees of effectiveness against symptomatic Covid-19 in trials, but they have all been shown to be effective in preventing serious illness and death.