The discrepancy, first reported by Reuters, centers on the regimen given to a smaller group of volunteers in late-stage trials, half a dose followed by a full dose. This differed from the original plan of two full doses, given to most of the participants.
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The half-dose pattern was found to be 90% effective, compared to the 62% success rate of the main study of two full doses, based on interim data.
AstraZeneca’s head of research told Reuters 10 days ago, when the trial’s interim data was released, half the dose was inadvertently administered as a first shot to some trial participants and emerged as a stroke of fortune, “serendipity.” , which scientists expertly harnessed.
However, this narrative was refuted by a leading Oxford University scientist, who told Reuters on Monday that the half-dose injection was deliberately administered after extensive consultation.
Uncertainty about how the dosing regimen came about raises questions about the robustness of the data, according to some experts who said it risked slowing down the process of obtaining regulatory approval for the injection and undermining public confidence.
“These different accounts are troubling,” Eleanor Riley, a professor of immunology and infectious diseases at the University of Edinburgh, told Reuters.
“Trust is a rare commodity when it comes to vaccines and we must not do anything that could undermine it in any way.”
There is also the potential impact on AstraZeneca, whose stocks have underperformed rival vaccine developers who have also announced successful results, in part due to scientists’ concerns about the relatively small sample size for the subgroup of media. dose that led to 90% efficacy. finding.
AstraZeneca declined to comment on the conflicting accounts.
A spokesperson for the University of Oxford said a media briefing would be held once the detailed interim results of the trial are peer-reviewed and published in a scientific journal.
“This will be the appropriate time to discuss the complicated complexities of global test design,” he said.
OXFORD SCIENTIST: ‘THAT IS NOT TRUE’
More than 20 countries, including many poorer countries, have ordered the vaccine, which costs less than some rival injections and is easier to distribute.
Data from the trial was released on November 23, when the developers hailed “a vaccine for the world.” Hours later, AstraZeneca’s head of non-cancer research and development, Mene Pangalos, told Reuters that the half-dose program had been a case of miscalculated dosing given to some volunteers.
It came to light, he said, after side effects in some participants turned out to be surprisingly mild.
“The reason we take half the dose is chance,” he said.
However, Professor Adrian Hill, director of the Jenner Institute at the University of Oxford, which co-developed the COVID-19 injection with AstraZeneca and led the UK trials, told Reuters in a telephone interview on Monday that it was a conscious decision of the researchers to administer a lower dose.
“There was some confusion suggesting that we didn’t know we were administering half the dose when we administered it, that’s really not true,” he said.
“What we knew was that we were using a different lot of a vaccine from a different manufacturer. We knew the measures and had been in discussions with regulators about how to move forward.
“The dosage that we started with that new batch was half the dosage compared to what we had used previously,” he added, without giving details about the different manufacturers.
Both the AstraZeneca and Oxford University scientists said they had consulted health regulators and given the go-ahead to continue the half dose among a limited group of volunteers in Britain, and follow up with the full-dose booster injection at the scheduled time. .
Britain’s Medicines and Health Products Regulatory Agency (MHRA) said its ongoing review of the vaccine is ongoing and that any vaccine must undergo robust clinical trials in accordance with international standards.
“No vaccine would be authorized for supply in the UK unless expected standards of safety, quality and efficacy are met,” said a spokeswoman. It did not comment on when the regulator was consulted about the half-dose regimen.
The European Medicines Agency did not respond to repeated requests for comment.
‘NEEDS TO BE CLEARED QUICKLY’
For Oxford vaccinologists, the confusion is a far cry from the euphoria of last week when interim data seemed to vindicate nearly three decades of work.
But the conflicting versions of events are the latest twist on the vaccine data, which has drawn scrutiny from scientists and investors since its launch.
“Whether or not they are accurate, and whether or not they affect the validity of the data released last week, needs to be quickly clarified,” Riley from the University of Edinburgh said of the conflicting accounts.
While US regulators have said that approval of a COVID-19 vaccine with a minimum 50% efficacy will be considered, Moderna and Pfizer-BioNTech have set a high bar, reporting efficacy data greater than 90%. for your vaccinations.
Independent scientists have expressed concern that the AstraZeneca-Oxford half-dose group, with just over 2,700 participants, was too small to produce a robust efficacy result.
That’s a fraction of the tens of thousands of trial participants that resulted in high-efficacy data from Pfizer-BioNTech and Moderna vaccines.
“All we have to go on is limited data release,” Peter Openshaw, professor of experimental medicine at Imperial College London, said last week. “We have to wait for the full data and see how the regulators view the results,” he said, adding that US and European watchdogs “could possibly have a different opinion” of each other.
AstraZeneca has lost nearly 7 billion pounds ($ 9.35 billion) in value since the results of the interim trial amid such concerns.
He has said that he hopes that more trial data collected over time in that group will solidify the interim findings. It is also considering a new global test based on the dosing pattern for clarity.
Oxford and AstraZeneca say they have submitted their reading to regulators around the world to seek marketing approval. They say the dosing pattern is also subject to discussion with regulators.
The university said last Friday it supported the idea of additional and ongoing trials, but added that interim analysis had already “shown the vaccine to be highly effective in a global study of 24,000.”
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