Actually the time is not the factor. Number of people involved is. These vaccine trials were large but you could not find something more after just waiting when

Actually the time is not the factor. Number of people involved is. These vaccine trials were large but you could not find something more after just waiting when something you are looking for is very rare. Should we have tested the vaccines on millions of people before rolling them out? How is it different from just rolling it out? Do you think that the approval would not have been given if current issues would have been found?