Pfizer vacx contains potassium chloride same used for lethal injection. Pfizer only specifies that is below 39mg, the problem is that when is injected into the body it is absorbed all, giving dangerous heart inflammation
https://en.wikipedia.org/wiki/Lethal_injection
Potassium chloride: a potassium salt, which increases the blood and cardiac concentration of potassium to stop the heart via an abnormal heartbeat and thus cause death by cardiac arrest.