A Target Trial Emulation study that tries to emulate the sequential specification of a target trial will be conducted measuring and controlling confounders when there is a common cause of vaccination and outcome event.~Participants will be provided with a Quick response (QR) code to access the RedCap study platform, which will guide them to the enrolment process. If the participant accepts and meets all the inclusion and none of the exclusion criteria, they will be directed to a baseline survey to self-collect sociodemographic data and information regarding risk factors, sexual behaviour, vaccination, and exposure to monkeypox.~Newly vaccinated participants will be matched 1:1 to unvaccinated controls. The matching will be performed based on the site of recruitment, and self-reported baseline sexual health and practices. Vaccinated and unvaccinated participants will be matched on variables associated with the probability of infection.~Follow-up will include regular surveys every month from the index date (i.e., enrolment date in the unvaccinated group, or vaccination date for the vaccinated group), to collect data on change on risk factors, sexual behaviour in the past month, vaccination status, and exposure to monkeypox. The participant will be asked to self-report if they develop symptoms suggestive of monkeypox, and the study platform will direct them to a specific monkeypox infection survey.~For each participant, follow-up will end at the earliest of the following events: monkeypox infection, voluntary withdraw, or the end of the study period. A health record review will be conducted to corroborate the diagnosis of new cases and to provide validity to the self-report.
The purpose of this study is to assess the protection of smallpox preexposure vaccination against infection with monkeypox in real-world individuals with risk factors for monkeypox.