AstraZeneca and Oxford University acknowledged on Wednesday that a manufacturing error has cast doubt on their recent announcement that their COVID-19 vaccine candidate was up to 90% effective.
The Monday announcement claimed that partial results from larger studies showed AstraZeneca’s vaccine had an average 70% effectiveness based on evidence that one dosage amount was roughly 90% effective and another was 62% effective.
In a Wednesday statement, Oxford University said that the manufacturing error had been identified before the late-stage trial was completed and that the team had decided to continue with the study split into two groups after discussing the problem with regulators, according to the Associated Press.
Experts, however, are concerned that the size of the two groups “makes it difficult to know if the effectiveness seen in the group is real or a statistical quirk. Fewer than 3,000 people received the more effective half-dose, whereas more than three times as many individuals, 8,895 total, received two full doses.
David Salisbury, an associate fellow of the Chatham House’s global health program, told the Associated Press that averaging those results is an inaccurate way of presenting the results of the study.
“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,″ he said. “I think many people are having trouble with that.″
Additionally, no one in the half-dose group was over the age of 55. Considering that younger individuals tend to fight off the coronavirus better than older people, it’s possible that age was just as or more significant a factor than the dose of the vaccine itself.
Pascal Soriot, the CEO of AstraZeneca, told Bloomberg on Thursday that the company will likely begin another global trial in the wake of those manufacturing errors.
“Now that we’ve found what looks like a better efficacy we have to validate this, so we need to do an additional study,” Soriot told the outlet. He said it will likely be an “international study, but this one could be faster because we know the efficacy is high so we need a smaller number of patients.”
A spokesperson clarified to NBC News that any further studies would “not [be] a brand new trial” but rather would be an expansion of the variable dosages.
“As we communicated in Monday’s press event there is strong merit in continuing to further investigate the half dose/full dose regimen,” the company said.
The Washington Examiner reached out to AstraZeneca for further comment.
