The COVID-19 vaccine from AstraZeneca fully staved off hospitalization and severe disease and did not produce blood clots or other safety problems in a large U.S. trial, the company reported Monday, giving the drugmaker a much-needed boost after hiccups in Europe.
The company said the vaccine was 79% effective in preventing all forms of COVID-19 disease. Notably, it was 80% effective in those over age 65, who made up a fifth of the trial. Elderly people are particularly vulnerable to the coronavirus.
“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,” said Ann Falsey, a professor of medicine at the University of Rochester School of Medicine and co-lead principal investigator in the trial.
AstraZeneca said it will prep its data and request emergency-use authorization from the Food and Drug Administration in the “coming weeks,” meaning it might not be available in the U.S. until May.
President Biden says by the end of May, the U.S. will have enough doses of three approved vaccines from Pfizer-BioNTech, Moderna and Johnson & Johnson for every American adult who wants to be immunized — although scheduling and administering the shots will take longer.
Already, the U.S. loaned 4 million doses of the AstraZeneca vaccine to Canada and Mexico, since they were just sitting in factories awaiting approval.
Still, a green light from American regulators would be a big PR boost for the vaccine, which is less expensive than other versions and has been earmarked as a critical tool in the fight against the virus in Europe and many developing countries.
The two-dose vaccine uses an adenovirus vector — basically an inactivated virus — as a vehicle for a gene that codes for the coronavirus, so the body mounts a response. The one-shot version from J&J also uses this platform.
Developed with Oxford University, the AstraZeneca vaccine was considered a front-runner in the race to wrangle COVID-19 but stumbled due to confusion over a set of trial participants who received a half dose at first. Then, the company and U.S. regulators struggled to work through concerns last year around an adverse event in the U.K.
Its biggest stumble came in recent days, as major European nations suspended their rollouts due to concerns the shots might be linked to thrombotic events, or blood clotting, reported in participants in some countries. However, the rate wasn’t beyond what would be expected in the background population, anyway.
European regulators concluded the shots were safe, though experts say the pause might have sown doubts in some people.
AstraZeneca said it specifically looked for thrombotic events among U.S. trial participants and found none.