Questions about the vaccine: The United States has ordered 300 million doses of the two-dose vaccine candidate, which has faced questions during development. An advanced stage trial was suspended this fall to assess a severe reaction to a shot, while promising results from an early reading on the shot were attributed to a dosing error.
Slaoui said that while the AstraZeneca vaccine appears to be very effective against serious illnesses, its effectiveness in the elderly is “indeed unknown” because few elderly people were enrolled at the start of the trial. He said that remained his biggest question on the company’s firing, given the impact of the virus on seniors.
British regulators on Wednesday morning became the first in the world to allow the use of the AstraZeneca vaccine. Rather than withholding doses to ensure people get a second vaccine quickly, UK health officials have said they will widely vaccinate the country with the first doses and deliver the second within three months. They said the move would provide some level of protection for the whole country amid climbing infections and a new variant of the virus that appears to be more transmissible.
But the effectiveness of the AstraZeneca vaccine is still unclear, especially when the doses are spaced out. So far, AstraZeneca’s vaccine shows 62% efficacy when used in two full doses given 28 days apart. But after a dilution error in one arm of a Phase 3 trial, scientists found that the vaccine was 90% effective when a small group first received half a dose.
US regulators need more evidence: The drugmaker said the combined results showed 70% effectiveness, but Slaoui suggested U.S. regulators would not be happy with the finding.
“As far as Americans are concerned, I think it’s important to say that one vaccine has 95 percent effectiveness, another vaccine has X percent, regardless of that number,” Slaoui told reporters, referring to the high efficacy rates of Pfizer and BioNTech and Moderna Vaccines that the FDA has cleared. “We need a clear, concrete number more than a number accumulated by adding up different trials with different timetables and different materials.”
Slaoui also questioned Britain’s dosing strategy. He said it was possible that a booster could be more effective when given months later, but said the UK decision was based on theory rather than evidence.
“It’s important, I think, to use the vaccine depending on how you’ve studied it,” he said.