Mpox among Public Festival Attendees, Chicago, Illinois, USA, July-August 2022

We investigated an mpox outbreak after a 2022 LGBTQ event in Chicago, Illinois, USA. Among case-patients, 38% had received 1 dose of mpox vaccine, none 2 doses; most reported sexual activity during the probable exposure period. Among other preventive measures, per-sons at risk should complete mpox vaccination 14 days before an event.

Automated summary

We investigated a measles outbreak after a 2022 LGBTQ event in Chicago, Illinois, USA. Among the confirmed cases, 38% had received one dose of measles vaccine and none had received two doses. Most of the cases reported engaging in sexual activity during the probable exposure period. As a preventive measure, individuals at risk should complete measles vaccination at least 14 days before attending an event.