Not sure why the downvotes, it's a legitimate question. So there's a phase to see if there are huge side-effects in humans, then a phase to see what dosage to

Not sure why the downvotes, it's a legitimate question. So there's a phase to see if there are huge side-effects in humans, then a phase to see what dosage to use for effectiveness, then a larger (tens of thousands) phase to get enough data to justify using it on millions of people. I think there are normally more phases after that when you're not in a pandemic.