We are always making decisions under conditions of uncertainty with imperfect information. In a pandemic, the information leaders have is even more uncertain given the rapid evolution of our understanding of the virus. These conditions require leaders to make difficult tradeoffs that have to maximize reward while managing risks. There is no ideal, only choices between competing second-best scenarios. Given these considerations, the decision of numerous European countries to suspend use of the AstraZeneca vaccine was a grievous error that will further inhibit Europe’s already anemic mass vaccination program. 

Two weeks ago, countries across Europe began pausing AstraZeneca shots due to reports of blood clots in people who had recently received the vaccine. Scientists in Denmark reported cases of rare and dangerous blood clots which forced the European Medicines Agency (the European Union’s version of our FDA) to call an emergency meeting. The EMA released its preliminary investigation into the available data a few days later, finding that “the vaccine is not associated with an increase in the overall risk of blood clots…in those who receive it.” The EMA made the right call, and after losing around a week and a half of vaccinations, some countries are beginning to resume use of the AstraZeneca vaccine. 

However, this pause and emergency investigation should never have occurred, as there was not sufficient initial evidence to raise doubt over the safety of the vaccine. Before approval, the AstraZeneca jab underwent rigorous safety and efficacy testing. No statistically significant blood clotting problems were reported. Around 20 million doses of the AstraZeneca vaccine have been administered worldwide. If blood clotting was a substantial risk factor, it is likely that this would have shown up in the data before now. This assessment has been confirmed by the EMA, who concluded its investigation this week and reported that the “Overall the number of [blood clotting] events reported after vaccination…was lower than that expected in the general population.” 

Polling data before this snafu demonstrated concerning levels of vaccine hesitancy across Europe. While regulators intended for the pause and investigation to reassure the public, the move could have the opposite effect and raise doubt in the minds of everyday people who don’t have the time or desire to review the statistical and scientific evidence demonstrating there isn’t an increased risk of blood clotting. Instead, the initial headline will leave a lasting and fear inducing imprint: Vaccine suspended over blood clotting fears. 

The countries claim they were acting precautionarily. In practice, this meant rejecting risk-benefit analysis in favor of absolute certainty. Instead of continuing with vaccinations until there was a scientifically demonstrated problem with the AstraZeneca shot, European bureaucrats paused the use of a life-saving vaccine in the absence of statistical evidence or scientifically demonstrated causality.

Notably, one country that didn’t nab the jab was Britain. Throughout the entire episode, the Brits continued using the AstraZeneca vaccine, maintaining that the demonstrated benefits of the vaccine in preventing infection, severe illness and death from coronavirus outweighed the unproven risks of increased blood clotting. The UK has taken a similar approach to vaccination more broadly, understanding the necessity to balance reward and risk and to not allow the perfect to become the enemy of the good. 

Soon after the first vaccines were approved, the British made a calculated decision with a high reward-to-risk ratio and became the first country to adopt a first-doses-first approach to vaccination, despite the method being unconfirmed by scientific study. Instead of holding doses back to provide people with their second dose, Britain prioritized giving as many first doses as possible because it realized that one dose of all of the vaccines provides over 95 percent protection against death. Thus, instead of raising one person from 95 percent 99 percent protection from death with a two-dose course, they raise two people from 0 percent protection to over 95 percent protection from death with two first doses. 

Consequently, EU countries have only vaccinated approximately 12.5 percent of their population, while the UK has given first doses to around 50 percent of its population. Along with recent scientific studies confirming the superiority of the British approach, the first-doses-first program has been vindicated through the plummeting number of infections in England while the rest of the continent undergoes another round of lockdowns.

European countries’ decision to pause AstraZeneca shots without sufficient scientific evidence will cause unnecessary death and delay the return to normal life for their citizens, all without any scientific evidence.