Campos‐Mercade 2021.

Study characteristics
Methods	Study design: randomised controlled experiment Type of publication: journal publication (online) Setting and dates: Sweden, May to July 2021 Countries: Sweden Language: English
Interventions	Monetary incentive: SEK 200 (about $24) conditional for becoming vaccinated Nudging:  Social impact condition: list four people who would benefit from the participant vaccinating Arguments condition: to write down arguments that could best convince another person to vaccinate (arguments condition) Information condition: participate in a quiz with information on the safety and effectiveness of COVID‐19 vaccines No reminder condition: No nudge or reminder
Population	Age: 18‐49 Gender: NR Ethnicity: NR Number of participants (recruited/allocated/evaluated): 8286 Inclusion/exclusion criteria: NR
Outcomes	Participants’ self‐reported intention to get a first dose of a COVID‐19 vaccine within 30 days after vaccines become available to them Whether participants vaccinated within 30 days according to the administrative records.
Notes	Funding: Danish National Research Foundation grant DNRF134 (PC), Swiss National Science Foundation Grant PZ00P1_201956(ANM), Swiss National Science Foundation grant 100018_185176 (FHS), Chazen Institute for Global Business at Columbia Business School (SM), Columbia Business School (SM), The Booth School of Business, University of Chicago(DP), and Riksbankens Jubileumsfond (EW) COI: none declared