The dose of AstraZeneca Plc’s Covid vaccine that showed the highest level of effectiveness was tested in a younger population than a bigger dose that showed less efficacy, according to the head of the U.S. Operation Warp Speed program.
The vaccine being developed with Oxford University was 90% effective when a half-dose was given before a full-dose booster, the partners said on Monday. However, that regime was administered to participants in a group whose age was capped at 55, Warp Speed’s Moncef Slaoui said Tuesday in a phone call with reporters.
Researchers have been puzzling about the AstraZeneca report since it was released, wondering why a smaller dose of the vaccine might have appeared to be more effective than a larger one. Most of the people in the trial received a placebo or the regimen of two full doses, which was 62% effective. That group included people who were older … Read More