Coronavirus: age cap in Oxford vaccine trials casts doubt over results

Oxford University and AstraZeneca are facing questions over their promising vaccine trial results after health officials revealed that key information about the ages of the test subjects was omitted.

During the Phase 3 trial, one group of test subjects was inoculated with two doses of the vaccine, spaced a month apart, while a second group was administered with a half-dose followed by a full one. In the first group, the protection rate was found to be 62%, but data from the second group showed that the vaccine was effective 90% of the time.

The reason for the wide discrepency has puzzled scientists. But they may now have their answer, after researcher Moncef Slaoui, who is spearheading the US’s vaccine distribution programme, told reporters that the age of participants in the second group “was capped at 55”, Bloomberg reports.

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No age breakdown was given in the reporting of the results, which have been cast into doubt over the omission of the most at-risk age demographics.

Former Pfizer research and development president Geoffrey Porges researchers “said he thought it was unlikely the AstraZeneca jab would get approval in the US after the company ‘tried to embellish their results’ by highlighting higher efficacy in a ‘relatively small subset of subjects in the study’”, the Financial Times reports.

Meanwhile, David Salisbury, an associate fellow of the global health programme at Chatham House, told The Telegraph: “You’ve taken two studies for which different doses were used and come up with a composite that doesn’t represent either of the doses. I think many people are having trouble with that.”

And the admission earlier this week by AstraZeneca that the half-dose was administered by error during the trials will add to “questions about whether the vaccine’s apparently spectacular efficacy will hold up under additional testing”, says The New York Times - which suggests that AstraZeneca’s “spotty disclosures have eroded confidence” in the jab.