Oxford-Astra COVID-19 Vaccine Shows Average 70.4% Efficacy in Pooled Study

A COVID-19 vaccine developed by AstraZeneca and Oxford University showed average efficacy of 70.4% in a pooled analysis of interim data from late stage trials, Oxford said on Tuesday.

Much anticipated study results, published in The Lancet medical journal, showed the candidate vaccine’s efficacy was 62% for those given two full doses, and 90% in a sub-group of trial participants given a half then a full dose.

That is above the 50% minimum set by the U.S. Food and Drug Administration.

AstraZeneca Chief Executive Officer Pascal Soriot said the drugmaker had begun submitting data to regulatory authorities around the world to seek early approval of the shot.

“Our global supply chains are up and running, ready to quickly begin delivering hundreds of millions of doses,” he said in a statement issued by Oxford University.

However, the Lancet study gave few extra clues about why efficacy was 62% for trial participants given two full doses, but 90% for a smaller sub-group given a half, then a full dose.

“(This) will require further research as more data becomes available from the trial,” the study said.

Less than 6% of UK trial participants were given the lower dose regimen and none of them was aged over 55, meaning more research will be needed to investigate the vaccine’s efficacy in older people who are particularly susceptible to COVID-19.

COVID-19 vaccines from Pfizer/BioNTech and Moderna have reported efficacy levels of more than 90% in late stage trials.

But the AstraZeneca/Oxford vaccine is seen as particularly important to tackling the pandemic in the developing world, as it would be cheaper and easier to distribute.

“The basic message that the overall efficacy across the trials that are reported here is about 70% but with a clear description of its uncertainty,” said Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine.

“The statistical uncertainty is that the efficacy could be as low as 55% or as high as 80%. The Pfizer/BioNTech and Moderna vaccines both have efficacies above 90% and are clearly more efficacious under trial conditions.”

Head of AstraZeneca’s non-oncology research and development, Mene Pangalos, said he hoped requests for approval from regulators around the globe could still be submitted this year.

“We hope that once the regulatory authorities review the data, we can get approval any time from the completion of the submission, which could be any time from the end of this year to early next year,” he said.

However, Pollard conceded the different results from the two dosage regimens complicated matters.

“The regulators will decide exactly what their label should say,” he said, when asked whether regulators might approve the two full shots regiment first, and then potentially the half, then full, shot regiment when more data is in.

Pangalos also said he assumed U.S. regulators would want to see results from an ongoing trial in the United States before giving their approval.

The Oxford researchers said the vaccine was found to be safe, with three out of the roughly 23,700 participants experiencing serious conditions that were possibly related to either the COVID-19 vaccine or a standard meningitis vaccine given to a control group.