“This is a large study, so these results can be expected to be robust. They could be expected to be even more so if there were more cases to compare between the groups, but 141 is still a substantial number of cases,” said Peter English, MD, of Horsham, United Kingdom, who is immediate past chair of the British Medical Association Public Health Medicine Committee.
Experts welcomed the 80% efficacy in people 65 and older in particular. “Importantly, the trial provides further support for efficacy in the elderly where previous clinical trial data, other than immunologic data, had been lacking,” Dr. Garrett said.
“It is clear this vaccine has very good efficacy. Remember that 60% was, prior to any trials being started, regarded as a good target,” said Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine. “This efficacy does not show a notable decline at older ages. This was expected and the speculation that it was ineffective or quasi-ineffective at older ages was totally unjustified.
“This is good news for the global community and one hopes that any political statements around this good news are avoided,” he added.
Efficacy against variants?
Regarding virus variants, Mr. Pangalos noted the study was conducted when several variants of concern were in circulation.
“What I can say is given this study was conducted much later in terms of timing, it’s very encouraging that we’ve got such high efficacy numbers when undoubtedly there are variants of concern in circulation in this study,” Mr. Pangalos said.
“It also highlights why we believe that against severe disease, our vaccine will be effective against all variants of concern,” he added.
Once the company submits its EUA to the FDA, the company is ready to immediately distribute 30 million doses of the vaccine and expects to ship 50 million total within the first month, Ruud Dobber, PhD, AstraZeneca executive vice president and president of the AZ Biopharmaceuticals Business Unit, said during the briefing.
The vaccine can be stored at 2 to 8 degrees Celsius for at least 6 months. Like other COVID-19 vaccines already authorized for emergency use, the duration of protection with the AstraZeneca product remains unknown.
This article was updated March 23, 2021.
A version of this article first appeared on WebMD.com.