Many European countries have paused the rollout of the AstraZeneca vaccine, due to a small number of reported blood clot cases in people who recently received the vaccine. Obviously any possible serious side effects need to be studied, but the decision to actually halt the use of the vaccine has its own costs. Let’s do some rough math.
The data is incomplete, but it appears that the most serious side effect being reported is cerebral venous thrombosis (CVT). This is a rare type of stroke which has been reported in seven cases (three fatal) in Germany, in patients who had recently been vaccinated with the AstraZeneca vaccine. Statistically you would expected only one case of CVT in the population of 1.6 million who received that vaccine in that time window.
Let’s assume that there really is a serious side effect, and that the vaccine raises the risk of CVT by 5 in a million. That’s one side of the equation. On the other side, you’ve paused the AstraZeneca vaccine rollout, which means more people will get COVID-19. Yes, there are other vaccines, but right now there are more people who want vaccine than there are vaccines available, so cutting of the AstraZeneca supply will reduce the vaccination rate. Let’s use Germany as an example.
Take 1 million Germans, give them AstraZeneca. Once they are immune, they won’t die of COVID.1Although the vaccine is ‘only’ 76% effective, it is 100% effective at preventing death from COVID And, for argument’s sake, let’s say that five of those one million Germans get CVT, and three of them die.
Instead, let’s delay the vaccines for those one million Germans. Say, two weeks. Germany is averaging about 10,000 new cases a day, in a population of about 80 million. Based on that rate, those one million Germans will get 1750 cases of COVID because of the two week delay. The Case Fatality rate of COVID these days is about 2%. That works out to about 35 deaths.
Now, there is some subtlety to this; if you’re young your chance of dying from COVID is very low, perhaps below the CVT risk. So maybe you don’t give the vaccine to people in their twenties. But otherwise, this does not look like a good tradeoff.
