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Astra Vaccine’s 90% Efficacy in Covid Came in Younger Group

  • Smaller dose was more effective than larger in study
  • Researchers have been struggling to understand results
Updated on

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.