AstraZeneca planning an extra global trial for vaccine amid questions

AstraZeneca’s COVID-19 vaccine looks as if it’s headed for an additional global trial as the drugmaker tries to clear up uncertainty and confusion surrounding favorable results in its current study.

The company wants the new test to confirm the 90 percent efficacy rate that the shot showed in a portion of an existing trial, CEO Pascal Soriot said. It’s favoring that option rather than adding an arm to a separate study that’s already underway in the U.S.

Questions are mounting over one of the fastest-moving shots after the company acknowledged that a lower dosage level that appeared more effective resulted from a manufacturing discrepancy. The company and its partner, the University of Oxford, didn’t initially disclose the error and other key details, leading to concern over their transparency.

“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 said in his first interview since the data were released. It will probably be another “international study, but this one could be faster because we know the efficacy is high so we need a smaller number of patients.”

Soriot said he didn’t expect the additional trial to hold up approval in the U.K. and European Union.

Clearance from the U.S. Food and Drug Administration may take longer because the regulator is unlikely to approve the vaccine on the basis of studies conducted elsewhere, especially given the questions over the results, Soriot said. Authorization in some countries is still expected before the end of the year, he said.

Astra and Oxford reported Monday that a lower initial dose of the vaccine, followed by a full dose, produced a 90 percent efficacy rate in a smaller set of participants, compared with 62 percent for two full doses.

A day after the data were unveiled, the head of Operation Warp Speed, the U.S. vaccine program, said that the regimen showing the higher level of effectiveness was tested in a younger population. He also said the half-dose was given to some people because of an error in the quantity of vaccine put into some vials. None of those details were disclosed in Astra or Oxford’s original statements.

Soriot disputed the idea that the half-dose regimen was an error, saying that after researchers realized the dosing discrepancy they formally changed the trial protocol with the blessing of regulators.

“I won’t tell you we expected the efficacy to be higher,” said Soriot. But “people call it a mistake — it’s not a mistake.”