AstraZeneca and Oxford University will likely conduct another trial of their COVID-19 vaccine after acknowledging a manufacturing error raised questions about preliminary results from its late-stage study.
The new trial is set to look at the efficacy of a lower dosage, which performed better than a full dose, Bloomberg reports.
“Now that we’ve found what looks like a better efficacy we have to validate this, so we need to do an additional study,” AstraZeneca CEO Pascal Soriot said.
Catch the best deals and products hand-picked by our team at Best Picks 
Soriot said the trial will most likely be conducted internationally and could be faster than the previous trial.
The new trial is not expected to delay the vaccine being approved by regulators in the UK and the European Union, Soriot said.
Earlier this week, it was revealed a group of volunteers that received a lower dose of the vaccine generated better results than those who received two full doses.
The company and university didn’t mention why some participants didn’t receive as much vaccine in the first of two shots as expected.
In the low-dose group, AstraZeneca said, the vaccine appeared to be 90 per cent effective. In the group that got two full doses, the vaccine appeared to be 62 per cent effective.
Combined, the drugmakers said the vaccine appeared to be 70 per cent effective but the way in which the results were arrived at and reported by the companies has led to pointed questions from experts.
The partial results announced on Monday are from large ongoing studies in the UK and Brazil designed to determine the optimal dose of vaccine, as well as examine safety and effectiveness.
The error raised concerns from experts, who said the relatively small number of people in the low dose group makes it difficult to know if the effectiveness seen in the group is real or a statistical quirk.
Another point of confusion comes from a decision to pool results from two groups who received different dosing levels to reach an average 70 per cent effectiveness, said Chatham House think tank associate fellow David Salisbury.
“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 of the figure.
“I think many people are having trouble with that.”
Details of the trial results will be published in medical journals and provided to UK regulators so they can decide whether to authorise distribution of the vaccine.
- with AAP