What's interesting is that most of the medicine we use is tested in 3 phases during clinical trials and it goes through maximum around 50000 people (some are tested on no more than 15-20k), before it is granted market authorisation. Then it enters the IV stage post-marketing assessment- where it's used in the public. As for the vaccines they are used on more than 1 000 000 000, so you can do the math. But the medicine are tested around 10 years, not like the vaccines which are 1-2 years old.