The most recent results of a possible COVID-19 vaccine developed by the University of Oxford and AstraZeneca indicate that it is safe and 70% effective, but questions remain about how well it can help protect those 55 and older, one key concern for a vaccine that health authorities around the world hope to trust due to its low cost, availability and ease of use.
However, experts say the vaccine is likely to be approved, despite some confusion in the results and lower levels of protection than other vaccine candidates have shown.
“What we can see seems reasonable, but it’s a bit more complicated than what we’ve seen so far,” said Dr. Buddy Creech, a Vanderbilt University researcher who helped test two other vaccines. “If this had been the first report to come out, the field would still be excited to have a vaccine.”
The Lancet medical journal on Tuesday published partial results of the vaccine’s trials in the United Kingdom, Brazil and South Africa: safety results in 23,745 participants and protection levels in 11,636.
The results are difficult to interpret because an error led some participants to receive a half dose followed by a full dose rather than two full doses as expected.
The researchers say the vaccine protected 62% of those who received two full doses and 90% of those who initially received half the dose against the disease. However, independent experts have said that the second group was too small (2,741 people) to judge the possible value of that approach and that more evidence is needed.
The group that received half a dose also did not include anyone older than 55, and among others in the study, only about 20% were in that age group.
It was unclear if the results will be enough to prompt regulators in the UK and other countries to approve its use immediately.
“We have no concerns about the safety of the vaccine,” as there have been no hospitalizations or critically ill people among those who received it, and results from all study sites show benefits consistently, said study leader Andrew Pollard of Oxford
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Associated Press journalists Maria Cheng and Danica Kirka in London contributed to this report.
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