Group Sex and Behavior Change Associated With the 2022 Mpox Outbreak Among Men Who Have Sex With Men in Southern California.

Background: The monkeypox (mpox) outbreak disproportionately affected sexually active gay, bisexual, and other men who have sex with men. To understand community-level changes in sexual behavior, we surveyed individuals in a semi-urban area in Southern California.

Methods: Participants were recruited between October 2022 and April 2023, using palm cards and geolocation-focused online advertisements on social media and dating apps. Eligible participants were male; 18 years or older; those who reported having sex with men; residents of San Bernardino or Riverside counties, California; human immunodeficiency virus (HIV) negative; and currently not taking preexposure prophylaxis. Descriptive analyses were performed. χ2 , Fisher exact, and Student t tests examined the association between group sex behaviors and demographics.

Results: We enrolled 91 gay, bisexual, and other men who have sex with men with a median age of 35 years (range, 18-70 years). Nearly half reported having participated in group sex in the past year. Overall, 48.9% of group sex participants reported changing their sexual behaviors to prevent mpox transmission, with limiting the number of sex partners being the most reported prevention strategy (47.6%). To prevent mpox infection, participants who engage in group sex reported limiting the number of sex partners (34.4%), using condoms for anal sex (16.7%), avoiding crowded social venues (14.3%), and asking partners about mpox symptoms before sex (9.5%).

Conclusions: Survey participants reported modest sexual behavior changes in response to the mpox outbreak. Group sex may increase the risk for mpox, human immunodeficiency virus, and other sexually transmitted infections; therefore, public health messages should include specific discussion of safer group sex practices in sexual health promotion.