AstraZeneca vaccine raises questions on shot that works better in small doses

Complexity leads to uncertainty in race for vaccine to end pandemic

AstraZeneca’s president of biopharmaceuticals  Ruud Dobber: 'Let’s be a bit more patient and see how the FDA will react'. Picture: University of Oxford

The news reached Sarah Gilbert on Saturday evening that the Covid-19 vaccine she’s developed with AstraZeneca appeared to work. But the University of Oxford professor had expected a key number: Was it more than 90% effective, as others have been — or less?

Instead, when her colleague Andrew Pollard called with the results, he wanted to show her slides rather than simple figures. “I didn’t really understand why we would have to go through slides,” she recalled. “But then it became clear — because it’s rather more complicated in our trial.”