The University of Oxford has more details about the mistake that led to his vaccination against the coronavirus being more effective



(REUTERS / Dado Ruvic / painting)
(REUTERS / Dado Ruvic / painting)

Aztrazeneka and the University of Oxford have explained more details about The manufacturing error that cast doubt on the preliminary results of his vaccine Experimental against COVID-19.

A statement describing the error was released days after the company and the university said the doses were “highly effective” and They did not mention the reason why some of the participants of clinical trial did not receive the expected amount of vaccine in the first of two injections.

In a surprising result, the group of volunteers who received the lower dose apparently received much better protection than those who received the two full doses.

In the lowest dose group, AstraZeneca, the vaccine was 90% effective. In the full dose group, it was 62%. In a combination, the pharmacist said the vaccine has a clear efficacy of 70%. However, the way the companies achieved and reported results have caused questions from some experts.

The partial results released Monday are based on extensive trials now in the UK and Brazil with the aim of determining the optimal dose of the vaccination, as well as examining the safety and effectiveness. Various combinations and doses were tested in the volunteers. The results were compared with those of groups that were vaccinated for meningitis or saline solution.

(REUTERS / Dado Ruvic)
(REUTERS / Dado Ruvic)

Have the researchers intended to provide a half dose?

Before saving their research, scientists specify all the steps to take and how they will analyze the results. Any change in this protocol can put the results in doubt.

In a statement released Wednesday, Oxford University said some of the vials used in the trial did not match the proper concentration of the vaccine, and that some volunteers received half-doses. The university said it had talked to regulators about the problem and agreed to end the advanced process with two groups. According to the text, the production manufacturing is fixed.

What about the results?

Experts say that the relatively low number of people in the low-dose group makes it difficult to know if the effectiveness that was recorded in the group is real or a statistical oddity.. About 2,741 people received a half dose of the vaccine, followed by a full dose at the second injection, AstraZeneca said. A total of 8,895 people received the two full doses.

Another factor: none of the people in the low-dose group is more than 55 years old. Younger people have a stronger immune response than older people, so it may be that the youth of the participants in the low-dose group is the reason for the favorable results, and not so much the volume of the dose.

Another point of confusion stems from the decision to pool the results of two groups of participants who received different dose levels to achieve an average effectiveness of 70%, said David Salisbury, a member of the Global Health Program at the Chatham Think Tank. House.

Oxford Vaccine Group Director Andrew Pollard at a Virtual Press Conference in Downing Street.  (November 23, 2020. REUTERS / Henry Nicholls)
Oxford Vaccine Group Director Andrew Pollard at a Virtual Press Conference in Downing Street. (November 23, 2020. REUTERS / Henry Nicholls)

“You take two studies in which different doses are used and you present a compound (with mixed results) that represents no dose,” he said of the figure. “I think a lot of people don’t like this procedure.”

Why would a smaller dose be more effective?

Oxford researchers say they are not sure and are working to find out why.

Sarah Gilbert, one of the Oxford scientists leading the research, said that The response is possibly related to giving exactly the correct dose of the vaccine to elicit the best immune response.

“I think the amount you like is like in the ‘Goldilocks’ story, not too much and not too small. Giving a very high dose may also generate a low quality response, ”he stated. “So, you want the right amount and it’s a bit of a hit and miss when you try to do it fast to get the perfect first time.”

Sarah Gilbert.
Sarah Gilbert.

What are the next steps?

Details of the trial results will be published in medical journals and given to British regulators so they can decide on permission for distribution of the vaccine.. The reports will include a detailed analysis that includes demographic and other information about who fell ill in each group, and will provide a more comprehensive picture of the effectiveness of the vaccine.

Monsef Sloy, who stands in the American program against coronavirus Operation Speed ​​Warp, Said in a conference call Tuesday that U.S. authorities are trying to determine the immune response generated by the vaccine, and may decide to modify the astronomical study in the United States to include half a dose.

“But we want it to be data-driven and science-based,” he said.

By DANICA KIRKA – AP

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