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The Oxford University / AstraZeneca vaccine is coming under increasing scrutiny, with critics questioning the claim that trials showed it could protect up to 90% of people against the coronavirus.
On Thursday, Sir John Bell, the Regius Oxford professor of medicine and UK government advisor for biological sciences, dismissed suggestions that the trial had not been properly organized or reported. “We were not preparing this as we went along,” he said, adding that he expected the full peer-reviewed data to be published in the Lancet medical journal over the weekend.
Despite public excitement over the announcement that a third vaccine had been successful, with particular promise for developing countries as it is relatively inexpensive and can be stored at refrigerator temperature, AstraZeneca’s share price fell. .
A US analyst wrote in an investor note that “we believe this product will never be licensed in the US.” And he alleged that the company had tried to “beautify” the results.
It comes after the leading figure for the vaccine’s overall efficacy was 70%, as announced by the company Monday and discussed at a press conference by Oxford researchers. But a subset of fewer than 3,000 people in the UK received a lower dose regimen, originally by accident, where the efficacy increased to 90%. In the majority of trial volunteers in Brazil and the UK, it was 62%.
Sir Mene Pangalos, AstraZeneca Director of Biopharmaceutical R&D, has confirmed that the low-dose trial did not include anyone older than 55 years. This raised concerns that younger age could have been a factor, particularly relevant given that the vulnerable elderly are at higher risk for Covid-19.
The researchers had no explanation for the 90% result in people who received a half dose followed by a full dose of the vaccine, rather than two full doses in other arms of the trial.
On Thursday, AstraZeneca said it would undertake a new global trial using the lowest dose regimen. The timeline for regulatory approval and launch of the vaccine in the UK and Europe should not be affected.
Critics have also claimed that the trials did not include enough ethnic diversity, gender and age balance to satisfy the US regulator, the Food and Drug Administration.
Advocating for vaccine trials, Bell said at a symposium hosted by the College of Pharmaceutical Medicine: “[The] MHRA [Medicines and Healthcare Products Regulatory Authority] He knew perfectly well what we were doing. They approved all the protocols. “
Before any of the vaccine trials reported results, it had been widely accepted that 60% efficacy would be sufficient for a license and would be useful, he said. “We are way above that. I can’t imagine any reason that regulators won’t accept it. “
The United States had not yet seen the full data, he said, and expected it to be published in The Lancet over the weekend. “I think when they look at the data, it will be a lot easier to have these conversations.”
The Oxford scientists and the company admitted that they were surprised by the finding that a lower dosage regimen performed better. Pangalos called it serendipity.
“It could be that by giving a small amount of the vaccine to start with and follow up with a large amount, that’s a better way to kick-start the immune system and give us the strongest immune response and the most effective immune response.” said Professor Sarah Gilbert, who led vaccine research at Oxford.
AstraZeneca’s CEO told Bloomberg that he would begin an international trial with the lower dose regimen, whereas previously it was expected to simply add an arm to the existing US trial.
The move will be seen as an attempt to satisfy the FDA and compete, if licensed in the US, with Pfizer and Moderna, which have published data suggesting 95% efficacy.
“Now that we have found what seems to be better efficacy [in the half dose/full dose regime], we have to validate this, so we need to do an additional study, ”CEO Pascal Soriot said Thursday. The study would probably be global “but this could be faster because we know that the efficacy is high, so we need a smaller number of patients.”
Peter Openshaw, professor of experimental medicine at Imperial College London, said more data would need to be collected if the trial’s low-dose group includes only those under 55.
“If this is true, it may mean that we do not have any information on this regimen in older adults,” he said. “We have to wait for the full data and see how the regulators view the Phase 3 test results. US and European regulators could possibly have a different opinion. All we have to do is publish limited data. “
He said the protection of the Oxford / AstraZeneca vaccine may be less than that of the Pfizer / BioNTech and Moderna vaccines, which were developed with a different RNA-based technology, “but we have to wait and see.”
Paul Hunter, a professor of medicine at the University of East Anglia and a methodology advisor to the World Health Organization, said he was always cautious about subgroup analyzes in trials.
“Most of the time, when you get these incredibly good results in a subgroup analysis, you have to be very careful to believe them,” he told The Guardian. There may be something in the smaller group that is not true in the larger group.
He was also concerned about the suggestion that the subgroup had no one over 55. “I’m not saying this is not a fantastic vaccine at the end of the day, but we need a better understanding of the data,” he said.
A spokesperson for AstraZeneca said that an independent data security monitoring board ensures the safety and quality of the tests. “The studies were conducted to the highest standards,” it said in a statement. “More data will continue to accumulate and additional analysis will be conducted to refine the effectiveness reading and establish the duration of protection.”
