AstraZeneca plans new vaccine trial as efficacy questioned
AstraZeneca said on Thursday it was likely to conduct an additional global trial to assess the efficacy of the Covid-19 vaccine it was developing along with University of Oxford after experts questioned its current studies and cited a lack of transparency around the late-stage clinical trials.
The announcement comes days after the vaccine developers said their two-shot inoculation was 70% effective in preventing Covid-19 in an interim analysis of their clinical trial, with a particular regimen in which the first shot was at half-strength showing a higher 90% efficacy.
“Now that we’ve found what looks like a better efficacy we have to validate this, so we need to do an additional study,” the pharma group’s chief executive officer Pascal Soriot told Bloomberg in his first interview since the data was 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”.
AstraZeneca and its partner Oxford University have been under pressure since the release of data on Monday, which initially raised hopes that billions around the world could have early access to a cheap coronavirus inoculation, but that has since been overtaken by confusion over what these disclosures mean.
The questions particularly surround the lack of information around the dose that uses a half-strength shot, which AstraZeneca executives later suggested was administered by mistake, and the split of infections among participants who were spread across two countries -- the United Kingdom and Brazil.
“We do not have enough information to know what to think. There needs to be a peer-reviewed publication and the company has to submit all its data to the FDA (US regulator Food and Drug Administration) and MHRA (UK’s Medicines and Healthcare products Regulatory Agency) for evaluation and approval,” said John Moore, professor of microbiology and immunology at Cornell University’s medical school, in a conversation over email with HT.
Moore said a new study with the half-strength dose was the only way to address some of the most pressing concerns relating to the efficacy estimates. “I believe the company CEO has said today that they will be doing that new trial. It makes sense,” he added.
How the vaccine performs is being closely watched in countries such as India, since AstraZeneca has committed a billion doses to the Covax facility to distribute vaccines to low- and middle-income countries. Among the producers of the vaccine is Pune-based Serum Institute of India, which has committed to supplying half of the doses it makes to the country.
According to a top expert, in India, where the vaccine is undergoing a separate late-stage trial, the approval can be filed on the lower-efficacy, two full-strength dose, which still meets the 50% efficacy bar set by regulators.
“Since the Indian trial is with two full doses of the vaccine, we can bridge to two full doses of the vaccine in the UK and Brazil and should not bridge to a dosing that we have not evaluated in India. Perhaps after the application to DCGI is done, they could propose additional studies in India, based on which they could apply for a labelling change,” said Dr Gagandeep Kang, former executive director, Translational Health Science and Technology Institute, a Department of Science and Technology (DST) organisation.
Kang said that the questions now being raised do not mean the trial results should be rubbished. “The results are good. Better than we hoped for when WHO, FDA and DCGI laid out the 50% efficacy point estimate criterion. All vaccine trials are different, and these are not head-to-head comparisons between vaccines that claim 90, 95 or 60 or 70% efficacy,” she added.
AstraZeneca’s CEO indicated on Thursday that the company is likely to follow through with this approach, telling Bloomberg that didn’t expect the additional trial to hold up regulatory approvals in the UK and European Union. Soriot also said that it was wrong the call the half-strength dose an error.
Oxford and AstraZeneca announced that their trial findings were based on 131 infections among 20,260 people split across trial sites in the UK and Brazil. The aggregate efficacy was 70.4%, but it was a much lower 62% among those who got the two full-strength doses as planned.
“AstraZeneca/Oxford get a poor grade for transparency and rigor when it comes to the vaccine trial results they have reported... AZN is evaluating their vaccine in multiple trials across the world, yet these are not embedded under a unified protocol. In fact, the trials seem to be quite different by country, in terms of populations, subgroups, etc,” wrote Natalie Dean, assistant professor of biostatistics at University of Florida, in a series of tweets on Wednesday.
According to a report in the New York Times, which was among the first to report these concerns on Wednesday, AstraZeneca executive Menelas Pangalos said the dosing error was made by a contractor and that regulators were notified of it and signed off on continuing to test the vaccine at different doses.
It is unclear what impact this controversy will have on approval process in India, which could itself depend on what regulators in the UK decide. “We need more time to better understand what is happening. If this vaccine is indeed less effective than others, the Indian government and people will need to decide whether it’s good enough for use. They are fully capable of making that decision when it’s time to do so, and based on as much information as possible - much more than we have now,” said Moore.
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