Want more details? We break it down into bite sized pieces below:
What’s happened?
In early March 2021, a slew of European countries paused administering the AstraZeneca vaccines after some reports of blood clots began to appear.
As per protocol, all severe adverse effects have to be investigated by the relevant medical authorities. When investigating, authorities look for signs of causation – did A cause B? Or did A and B happen to occur at the same time?
Most often, they do this by analysing the rates of occurrence of the event in the general population (or in the specific demographic) and then compare that to the rate of occurrence in the corresponding vaccinated population.
Here’s a simplified fictional example of what that means:
In the general population, say 1% of people over 50 suffer from heart attacks in a one month time period. In the vaccinated population, if this rate is the same or lower, then the event is deemed to not be caused by the vaccine. But if this rate is higher in the vaccinated population, then further investigations or ending of the vaccine trials or drives are required.