Experts in space medicine meet

London.- AstraZeneca and the University of Oxford on Wednesday acknowledged a manufacturing defect that casts doubt on the preliminary results of their experimental vaccine against COVID-19.

One statement describes the error that occurred days after the company and university described the injections as “very effective” and it did not mention why some study participants did not receive as many doses in the first vaccine of the two injections as expected.

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Surprisingly, the group of volunteers who received one lower dose turned out to be much better protected than the volunteers who received two full doses. In the low-dose group, he said AstraZeneca, the vaccine turned out to be one 90% efficiency. In the group that received two full doses, the vaccine was one 62% efficiency. Combined, the drug makers said the vaccine had a 70% efficiency. But the way companies arrived at and reported results has raised sharp questions from experts.

The partial results announced Monday come from large ongoing studies in the UK and Brazil designed to determine the optimal vaccine dose and to investigate safety and efficacy. Multiple combinations and doses were tested in the volunteers. They were compared to others who received meningitis vaccine or saline solution.

Are you only going to give half the dose?

Before starting their research, the scientists describe all the steps they will take and how they will analyze the results. Any deviation from that protocol could call the results into question.

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In a statement, Oxford University said on Wednesday that some of the vials used in the trial did not have the correct vaccine concentration, so some volunteers were given half doses. The university said it discussed the issue with regulators and agreed to complete the final phase of the two-group trial. According to the statement, the manufacturing problem has been resolved.

Experts say the relatively small number of people in the low-dose group makes it difficult to know whether the observed efficacy in the group is real or a statistical whim. About 2,741 people received half a dose of the vaccine, followed by a full dose, he said. AstraZeneca. In total, 8,895 people received two full doses.

Another factor: None of the people in the low-dose group were over 55 years old. Younger people tend to elicit a stronger immune response than the elderly, so it may be that the youth of the participants in the low dose group was the reason it seemed more effective, not the size of the dose.

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Another point of confusion arises from the decision to merge the results of two groups of participants who received different dose levels to achieve an average dose effectiveness. 70%said David Salisbury, associate member of the global health program at Chatham House think tank.
“He’s done two studies that used different dosages and created a compound that represents neither,” he said of the figure. “I think a lot of people have a problem with that.”

Researchers of Oxford They say they are not sure and are trying to find out why.

Sarah Gilbert, one of the Oxford scientists who led the study, said the answer likely has to do with providing just the right amount of vaccine to elicit the best immune response.

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‘It is the amount you want, I think, not too little and not too much. Too much can also give you a bad reaction, ”he said. “So you want the right amount and it’s a bit hit and miss when you try to go fast to get perfect the first time.”

Details of the study results will be published in medical journals and provided to UK regulators so they can decide whether to allow the distribution of the vaccine. Those reports will include a detailed breakdown with demographic and other information about who became ill in each group, and will provide a more complete picture of how effective the vaccine is.

agv / rcr

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