LONDON – AstraZeneca and the University of Oxford on Wednesday admitted a manufacturing error raising questions about the preliminary results of their experimental Kovid-19 vaccine.
A statement came a few days after the company and university described the shots as “highly effective” and made no mention of why some study participants did not receive the vaccine as expected in the first two shots.
Surprisingly, the group of volunteers receiving the low dose found it much better than the volunteers receiving the two full doses. In the low-dose group, AstraZeneca said, the vaccine appeared to be 90 percent effective. In the group receiving two full doses, the vaccine appeared to be 62 percent effective. Combined, drug manufacturers said the vaccine appeared to be 70 percent effective. But the way the results came and were reported by the companies, experts are starting to raise pointed questions.
Partial results announced on Monday are from large studies in the UK and Brazil designed to determine the optimal dose of the vaccine, as well as examine safety and effectiveness. Several combinations and doses were tried in volunteers. They were compared to those given the meningitis vaccine or saline shot.
Did the researchers mean to give half the dose
Before they begin their research, scientists explain all the steps they are taking, and how they will analyze the results. Any deviation from that protocol may put the results in question.
In a statement on Wednesday, Oxford University said some vials used in the test did not have the correct concentration of the vaccine, so some volunteers received one half dose. The university said it discussed the problem with regulators, and agreed to complete late-stage testing with two groups. According to the statement, the manufacturing problem has been fixed.
What about the results themselves
Experts say the relatively small number of people in the low-dose group makes it difficult to know if the effectiveness seen in the group is real or a statistical circle. AstraZeneca reported that 2,741 people were given half the dose of the vaccine. A total of 8,895 people received two full doses.
Another factor: no person in the low-dose group was older than 55 years. Younger people mount a more robust immune response than older people, so this may be why youngsters in the low-dose group appear to be more effective, not the dose size.
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At another point, deciding to receive different dosage levels from two groups of participants creates confusion, said David Salisbury, who is an associate of the Global Health Program at Chatham House think tank in the form of.
“You’ve done two studies for which different doses were used and came up with a composite that doesn’t represent either dose,” he said of the figure. “I think a lot of people are upset by this.”
Why would a small first be more effective?
Oxford researchers say they are not sure and they are working to uncover the cause.
Sarah Gilbert, one of the Oxford scientists who led the research, said the answer relates to providing the correct amount of vaccine to trigger the best immune response possible.
“It’s the Goldilocks amount you want, I think, not too little and not too much. A lot can also give you a poor quality response,” he said. “So you just want the right amount and it’s a little Hit and remember when you’re trying to go early to get that perfect for the first time. “
What are the next steps?
Details of the test results will be published in medical journals and provided to UK regulators to decide whether to authorize the delivery of the vaccine. Those reports would include a detailed breakdown that included demographic and other information about who became ill in each group, and give a more complete picture of how effective the vaccine is.
Monsef Saloi, who led the American Coronovirus vaccine program Operation War Speed, told reporters Tuesday that US officials are trying to determine what immune response the vaccine is producing, and to include half that In the US, AstraZeneca may decide to revise the study. Dosage.
“But we want it to be based on data and science,” he said.