>>13782047Because there's a cut-off threshold for incidence in positive cases. Drugs usually take long to test because
a) the target population is small (e.g. in rare genetic disorders)
b) the pathogen in not prevalent (e.g. ebola)
c) an alternative viable therapeutic exists which must then by law be used as the placebo arm, meaning incidence remains low in the control group
d) base immunity is present so incidence remains low in both placebo and treatment arms of the study
e) little funding or man power is available to conduct the study
For the study of the current vaccines, literally none of the above applied. The pathogen was widespread, everyone was susceptible to infection, no preventative therapeutics existed yet, and a fuckton of money was going into the development of these vaccines.
