The EUA expansion for Pfizer BNT162b2 vaccine for kids aged 12–15 was done after it failed (as I will show below) its pro-forma clinical trial.
Only 1,131 kids received at least one injection of the experimental vaccine. Most of them experienced side effects. Within a few days after the second shot, 66% of the kids developed fatigue, 65% developed headaches, 42% developed chills, and so on.
The first shot was tolerated only slightly better. Symptoms varied from mild to severe. More than half of the kids had to resort to painkillers or antipyretics after the second injection.
Given such frequency and severity of adverse effects, the sponsor had to either stop the trial because of safety, or to significantly increase its size to exclude high likelihood of death.
At the trial size, if the risk of immediate death were 1 per 1,000, the trial had only a 32% probability of missing it. We are lucky that this is not the case....