Spike in mpox cases in Chicago prompts warning from city health officials
October 10, 2025
Chicago’s recent rise in mpox cases is a stark reminder that vigilance and vaccination remain critical. The city recorded 100 infections between July and September, primarily among men aged 18 to 64, with two hospitalizations reported. While no Clade I cases have been detected, health officials warn that Clade IIb—the strain behind the 2022 global outbreak—continues to circulate. The Chicago Department of Public Health is expanding vaccination events and urging eligible residents to complete both JYNNEOS doses. Preventing another large-scale resurgence will depend on early vaccination, community education, and sustained outreach to at-risk populations, especially within social and sexual networks.
The Chicago Department of Public Health (CDPH) is sounding the alarm after confirming 100 new mpox cases between July and September, with 55 occurring in September alone. The majority of infections are among men aged 18 to 64, echoing patterns seen during the 2022 global outbreak caused by the Clade IIb strain. Although no cases of the more severe Clade I variant have been identified in Chicago, the current uptick signals the virus’s persistence and the need for renewed preventive measures.
Since the city began tracking mpox in 2022, more than 1,400 cases have been recorded, resulting in 86 hospitalizations and four deaths. The CDPH, in coordination with the Centers for Disease Control and Prevention (CDC), has emphasized vaccination as the most effective defense. The two-dose JYNNEOS vaccine, administered 28 days apart, offers strong protection when both doses are completed. Individuals exposed to mpox or within at-risk networks—particularly gay, bisexual, and same-gender-loving men with multiple or anonymous partners—are urged to get vaccinated immediately.
Mpox spreads primarily through skin-to-skin contact, contaminated materials, and prolonged face-to-face interactions. Pregnant women can also transmit the virus to their newborns. Symptoms typically include a painful rash and flu-like illness, and while many cases are mild, severe disease can occur in those with weakened immune systems.
To improve access, CDPH is organizing free vaccination events throughout October and directing residents to its online vaccine finder for additional locations. The renewed effort reflects lessons learned from the 2022 outbreak: timely vaccination, community engagement, and targeted communication are essential to containment. As global mpox transmission continues, Chicago’s proactive response serves as both a local safeguard and a reminder that public health preparedness requires continuous attention, not complacency, even after outbreaks appear to wane.