Transmission potential of human monkeypox in mass gatherings

Since May 2022, a large number of monkeypox cases has been reported in non-endemic settings. Taking into account the strict measures implemented due to the COVID-19 pandemic and the desire of people to reclaim what is perceived as lost time, it is anticipated that mass gatherings this summer will be highly attended. Based on data for the secondary attack rate among unvaccinated contacts from endemic countries, we estimate that, on average, more than one secondary case is anticipated per infectious person if he/she has a high number of group contacts (>30) or more than eight close contacts. Although the role of group contacts in mass gatherings is uncertain (less likely to involve physical contact, shorter duration), close contacts associated with the event (e.g. intimate/sexual contact with other attendees) might be the amplifying event. Enforcing awareness, early recognition and engaging affected populations in the monkeypox response are important to control transmission.