The problem is not discovering the vaccine, it is ensuring it is safe. See the recent Dengue vaccine incident of what can go wrong when new vaccines are rolled

The problem is not discovering the vaccine, it is ensuring it is safe. See the recent Dengue vaccine incident of what can go wrong when new vaccines are rolled out without proper caution: https://en.m.wikipedia.org/wiki/Dengvaxia_controversy https://en.m.wikipedia.org/wiki/Dengvaxia_controversy