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However, the scientific community, mainly in the US, got caught up in data transparency issues. And it is very likely that these issues will become an obstacle to the emergency registration of this vaccine with the responsible American and European institutions.
AstraZeneca announced on Monday that study participants living in the UK had different vaccination rates. It is true that at that time it was not explained why there were two different dosing regimens and why one group of subjects was much smaller than the other.
In a group of 2,741 subjects, participants received a first dose of vaccine reduced by half and a second full dose. In this group, the vaccine was 90 percent effective in protecting against COVID-19.
In the second group of 8,895 subjects, the volunteers received two full doses of the vaccine, at least one month apart. Statistical analysis shows that 62% was achieved in this group. efficacy level of the vaccine.
The sum of the results for both groups is the number published by AstraZeneca: an average efficiency of 70 percent.
However, some researchers wonder: why is the company publishing the overall results of clinical trials when in fact two different studies were conducted? This practice is not common for the publication of clinical trial results.
The most confusing things became clear in the last days.
On Tuesday, Ms Pangalos, executive vice president of AstraZeneca, who ran non-cancer research and development programs, explained to Reuters that a lower first dose of the vaccine was mistakenly administered by mistake. “The reason we take half a dose is a successful mistake,” Pangalos said, adding that the researchers “predicted the need for half a dose of the vaccine.”
In a statement issued Wednesday, the director of vaccine communication at the University of Oxford told CNN that “selecting the dose for any new vaccine is a very difficult area, and when we tested different dosing methods, we found that one method chose a lower dose than expected. “
On Thursday, representatives of the university clarified the situation again, telling CNN that the error was due to “differences in production processes.” The same comment stated that a manufacturing defect had been rectified and noted that the UK Medicines Regulator, which oversaw the conduct of this study, had allowed both study groups to be included in the results of the phase III clinical trial.
The fact that the division of the subjects into several groups was not a pre-planned step but an error was not mentioned in the report distributed on Monday, therefore both the company and the university were criticized for the lack of transparency. However, AstraZeneca responded to this criticism by saying that it was convinced that attention should be paid to the positive results of the study.
Pangalos told the Wall Street Journal on Wednesday that “In fact, that mistake is not important. Whatever segment of data you do, even if you only believed both full dose data, the efficacy limit required for the vaccine is approved is still 60 percent, “said Pangalos.
The US Food and Drug Administration (FDA) requirement for the vaccine’s effectiveness is less, at least 50 percent. But so far, it is difficult to say whether the FDA will register a vaccine developed in Europe on an emergency basis.
The AstraZeneca vaccine has yet to be tested in a half-dose clinical trial in the US, but a company spokesperson said Thursday that the goal was to use the half-dose in a US study that currently has around 10,000 participants.
A company spokesperson said a total of 40,000 volunteers are expected to be invited to the study, some of whom would receive half the dose of the vaccine. He added that discussions on FDA approval are currently ongoing and there is no formal knowledge on the matter yet.
Member of the FDA Advisory Committee on Vaccines and Related Biologics dr. Paul Offit, who himself reviewed the data on COVID-19 vaccines before granting them access to the public market, said the lack of data led to a forced decision that “it is difficult to clearly understand the importance of these results.”
The other two drug makers did not release the preliminary data from their vaccine studies, Pfizer and Moderna, on which those statements were based.
AstraZeneca published an analysis of data from 23,000 participants from phase III clinical trials.
This study description states that some volunteers received the COVID-19 vaccine from the study, while others received a different vaccine to protect against a completely unrelated virus (performed a placebo function).
A total of 131 participants developed COVID-19 symptoms among these subjects.
One of the most serious questions related to this study is why the difference in dosage regimens led to such a large difference in efficacy.
Andrew Pollard, the Oxford University professor who led the clinical trial, told reporters Monday that this is likely due to a fragile dosage balance that hits exactly the threshold necessary to trigger an immune response against the disease.
“With vaccines, we are constantly trying to push the immune system to think that a dangerous infection has entered the body to respond to, but we are doing it in a very safe way,” explained the professor.
Therefore, according to her, it may be that the best way to stimulate the immune system to act is to give the body a small amount of vaccine first and then a large amount.
Hearing the question of whether you sincerely believe that 90 percent. the efficiency indicator is a real hit and not just a statistical deviation due to a small sample, Pollard said, the result was “very significant, even with the numbers we have.”
However, experts doubt that the same result will apply if a lower dose regimen is applied to a greater number of people.
Moncef Slaoui, an expert in charge of the US COVID-19 vaccination program, said that data released by AstraZeneca is being analyzed. He said in the group that mistakenly received a first dose of the vaccine in half reduced and achieved 90 percent. efficacy, there were more younger patients; there were no subjects older than 55 years. This may have affected the reliability of the AstraZeneca results, as young people are generally known to have a stronger immune response to vaccines.
Representatives from the University of Oxford and AstraZeneca told CNN on Thursday that they could not provide an age breakdown for this smaller group of patients who received the lowest first dose.
A spokesperson for AstraZeneca said that “after evaluating the efficacy that we have seen with the different dosing regimens, there is a solid basis to continue research and test these findings to determine the most effective dosing regimen for the vaccine.”
He added that the company is currently in discussions with drug regulators in various jurisdictions regarding the evaluation of its results and intends to publish the peer-reviewed results of its clinical trial.
However, a vaccine specialist from Yale School of Medicine (USA), Dr. Saad Omer said he was convinced that a group with 90 percent. The efficacy rate was relatively low and that level of efficacy is unlikely to be sustained with a growing number of studies.
“I really don’t like to criticize colleagues in academia, or anyone in general, but publishing this kind of information is like making us read tea leaves.”
The market reacted negatively to the vaccine effectiveness data released by AstraZeneca: The company’s shares have fallen more than 6 percent since Monday.
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