First, Do Harm
Supporters of these types of experiments — called human challenge trials or controlled human infection models — argue that they are the quickest and cheapest way to develop new vaccines, test medicines and study the basic progression of some of humanity’s most enduring infectious foes, as well as some new ones. A major benefit of human challenge trials is that, because they deliberately cause infection, vaccines can be verified using far fewer people — in the Zika case, perhaps just 200, says Diamond, who cowrote an update on Zika vaccine development in the 2019 Annual Review of Medicine. In November 2018, the Wellcome Trust invited proposals for further human challenge trials to run against more diseases endemic in low- and middle-income countries.
Source: www.knowablemagazine.org