On Wednesday, AstraZeneca and Oxford University has acknowledged a manufacturing error. Now, this has raised questions on their experimental COVID-19 vaccine and its preliminary results.
Now, they have released a statement that described the manufacturing error. It was a few days after the company, as well as the university, stated that the shots given are highly effective. There was no mention of why some of the study participants could not receive the vaccine in the first two shots as they expected.
To our surprise, a team of volunteers got a lower dose and seemed to have given better protection than the volunteers who received two full doses. Among the low dose group, the vaccine exhibited 90 per cent effectiveness as well as AstraZeneca. But, in the other group, which was given two maximum doses, the vaccine resulted in just 62 per cent effectiveness. So, when they consider the average, the vaccine seems to be 70 per cent effective overall. Even after the experiment, the way results arrived and how it is reported has raised several questions from experts.
On Monday, the partial results were announced, and it was the results of extensive ongoing studies conducted in the U.K. and Brazil. The classes were focused and designed to determine the optimal dosage of vaccine and examine its effectiveness and safety. Hence they tried multiple doses and combinations on the volunteers. Later they were compared to others for whom saline shot or meningitis vaccine were given.
Why half dose? Why did they consider half dose?
Before starting their research, researchers have spelt out the steps they are taking in the experiment and how they analyze the results. When there exists some deviation in the protocol, the same can put the results in question.
On Wednesday, in a statement, Oxford University said, ‘Few of the vials utilized in the research and used on the volunteers in the trial were not filled with the right concentration of vaccine. Hence some of the volunteers were given half dose.’ As per the university, they have already discussed the problem with the respective regulators, and now they have agreed to finish the late-stage trial for two groups. According to the statement, the problem with manufacturing has been corrected.
Then what happened to the results?
Based on experts, there were a small number of people in the group for which they gave half dose. Hence the results or effectiveness is hard to decide and considered statistical quirk or real. Two thousand seven hundred forty-one people in the group took half the vaccine, but 8,895 people were given full dose.
There is another factor to be considered, and that is the age of the people in the small group. The people present in the low-dose group were all young, and none of them was more than 55 years old. As per experts, younger people will pose stronger immunity compared to older people. It can be the age of the people in the low-dose group that resulted in higher effectiveness and not the dose.
An associate fellow of the global health program, David Salisbury at the Chatham House think tank, said, ‘there is one more point that created confusion and came from the decision to pool results taken from two different dosed groups and ended up with 70 per cent effectiveness. You have considered two different groups wherein different doses were utilized. You have come up with a combined result that doesn’t represent either of the group or dose. I feel many people may have a problem with that.’
Why is low-dose more effective?
As per Oxford researchers, ‘we have no clarity, and we are working to reveal the same.’
Sarah Gilbert is among one of the Oxford scientists, and she was leading the research. She said, ‘the answer is completely related to deciding the right amount of vaccine that can actually trigger the best immunity response. It is nothing but the Goldilocks amount that people need. I think not too much, but not too little. When too much is given to some volunteer, that can give a poor quality response. Hence, the right amount should be decided, and there will be a hit and miss when trying to get the perfect dose at the perfect first time.’
Next step: What will it be?
Details of the current trials are noted, and they will be published in medical journals. Later the journal and the details are provided to U.K. regulators. After that, they will decide whether to authorize the vaccine distribution or not.