Summary of the mpox outbreak in Canada, April 28-December 31, 2022.

Abstract

Background: Mpox is an infectious disease caused by the monkeypox virus (MPXV), closely related to the virus that causes smallpox. In May 2022, cases of mpox were reported in previously non-endemic countries including Canada.

Objective: To summarize the epidemiology of the mpox outbreak in Canada, as well as key public health response activities, between April and December 2022.

Methods: The Public Health Agency of Canada (PHAC) worked closely with local, provincial and territorial public health authorities to develop national case investigation and reporting tools, including national case definitions for confirmed and probable mpox cases. Based on de-identified case data submitted to PHAC, patterns and trends were examined, including the distribution of cases by sociodemographic, clinical and transmission factors.

Results: Overall, 1,474 mpox cases (1,396 confirmed, 78 probable) were reported to PHAC. All reported cases were associated with MPXV clade IIb. Mpox disproportionately affected gay, bisexual and other men who have sex with men (80.0%) and those between 20-49 years of age (86.0%). Available data suggests that the most likely mode of disease acquisition was through sexual contact, with limited evidence on other possible modes of transmission. Some cases were hospitalized (3.0%); however, there were no mpox-related deaths in Canada.

Conclusion: Rapid coordination and surveillance activities supported the timely implementation of tailored interventions, including the procurement and distribution of vaccines. These actions, coupled with vaccination uptake and behavioural changes, contributed to reducing transmission and health impacts of mpox on the Canadian population.