Challenge trials can be ethically designed, and they have been used to test vaccines for malaria, influenza, and other potentially-fatal diseases. https://en.w

Challenge trials can be ethically designed, and they have been used to test vaccines for malaria, influenza, and other potentially-fatal diseases. https://en.wikipedia.org/wiki/Human_challenge_study#Vaccines_for_viral_infections https://en.wikipedia.org/wiki/Human_challenge_study#Vaccines...