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The lowest dose of the COVID vaccine, which was 90% effective during the Oxford and AstraZeneca clinical trials, was administered to younger subjects than the highest dose, which was shown to be less effective, he said. Operation Warp Speed in the United States, Moncef Slaoui, cited by Bloomberg.
The vaccine developed with the University of Oxford has been shown to be 90% effective in cases where a half dose was initially given, followed by a full booster dose, the researchers said Monday. Slaoui said this regimen was administered to participants in a group whose age was limited to 55 years.
The researchers wondered why a lower dose of the vaccine appeared to be more effective than a higher one. Most of the people in the study received a placebo or a two-dose full-dose regimen, which was 62% effective. This group included people over the age of 55, Slaoui explained.
“I don’t think the FDA (US Food and Drug Administration) has a positive view of a study where the dose, age group, or any other variable was changed in the middle of the process, by mistake or deliberately”. said Geoffrey Porges, an analyst at SVB Leerink, who believes the FDA will not approve this vaccine.
AstraZeneca stated that the data will be published and subject to timely expert review. The company’s shares fell as much as 2.2% in New York.
On Monday, when AstraZeneca released the results of the clinical trials, it did not give an age breakdown for the two groups. Slaoui said that half of the starting dose was given to the participants by mistake.
“There are a number of variables that we need to understand and see what the role of each of them was in making the difference in effectiveness,” Slaoui said.
Older people have a weaker response than some younger people to some vaccines, such as flu shots. Results from a phase 2 study of the AstraZeneca-Oxford vaccine published last week in the Lancet medical journal confirmed a strong response to the vaccine in the elderly.
Editing: Monica Bonea
