Not a good or recent one, but reading the linked article indicates the sort of trials being done for vaccines will have a median much greater than the $19 milli

Not a good or recent one, but reading the linked article indicates the sort of trials being done for vaccines will have a median much greater than the $19 million you cite. These trials enroll 30,000 subjects at minimum, and take 2 years, both of which substantially exceed the maximums cited in the paper that they or anyone else they knew of had tried. In the case of length, by 4 times. Thinking further, a billion is too high an estimate today, because these trials or one I looked closely at use smartphone "ediaries" to reduce the number of direct person to person contacts. But they're still high touch affairs, nothing substitutes for phone calls and direct examinations, although the latter are limited in number, but start with a general medical exam. Thanks for bringing that paper to my attention, I'll look more closely at it later.