The AstraZeneca COVID-19 vaccine is indispensable right now. As one of the first vaccines out of the gate, it’s been at the center of the World Health Organization’s plan to roll out some 2 billion doses to 92 nations by the end of the year. It’s also one of just a handful of vaccines that are already being produced and distributed on such a massive scale that they might change the near-term course of the pandemic.
That’s why the past few weeks have felt so catastrophic.
The run of bad news might have seemed, at first, to be short-lived. Earlier this month, regulators in more than 20 European countries suspended distribution of the AstraZeneca vaccine. The English-language media cited scattered reports of “blood clots” in recipients as the reason. A few days later, though, the European Medicines Agency’s expert committee weighed in to recommend the vaccine’s continued use. With COVID-19 case rates surging across Europe and more than 3,000 deaths a day, the group concluded that its benefits far outweighed any known or potential risks.
Just that short pause sparked despair and condemnation. Commentators and public-health experts called it “stupid, harmful, “quite dangerous,” and a “magnificent example of European failure.” The problem, they said, was that the actual evidence of harm had been very weak—and maybe even nonexistent. Writing in The New York Times on March 22, Heidi Larson, the director of the Vaccine Confidence Project at the London School of Hygiene & Tropical Medicine, noted that just 25 Europeans had developed blood clots, out of 20 million who received the AstraZeneca vaccine. That rate, she said, was lower than what you’d normally see among unvaccinated people. According to the statistician David Spiegelhalter, the furor over blood clots showed our “basic and often creative urge to find patterns even where none exist.”