Mpox outbreak control indicators used in Ontario, Canada: May 21-December 10, 2022

Since May 2022, over 91 000 cases of mpox have been reported globally with the majority of cases occurring among adult males who identify as gay, bisexual, or men who have sex with men (gbMSM). Given the rapid emergence of the global mpox outbreak, many public health authorities did not have established mpox outbreak control indicators or criteria for declaring an mpox outbreak over. Expert consensus in Ontario, Canada, set thresholds for five key indicators of mpox outbreak control as follows: estimated number of currently infectious cases < 5; effective reproductive number < 1.0; doubling time > 42 days; weekly test positivity < 5%; and sporadic non-gbMSM cases (i.e., female and pediatric cases). Once all indicators were achieved, a 52-day period based on two incubation periods for mpox and a 10-day reporting delay was employed to monitor for indicator stability. After all five indicators remained at expected levels, the mpox outbreak in Ontario was declared over on December 10, 2022. Despite current low levels of mpox activity globally, some jurisdictions may benefit from utilizing or modifying these outbreak control indicators during a future localized mpox outbreak.