lots of research on how to "combat vaccine hesitancy" – i.e., how to sway the hold-outs to become part of a medical experiment
https://static1.squarespace.com/static/5d4d746d648a4e0001186e38/t/5f7597a2fcfe7968a6b82efd/1601542158415/sabin+aspen+report+2020+meeting+the+challenge+of+vaccine+hesitancy
https://www.vaccineconfidence.org/research-feed/convince