A global systematic evidence review with meta-analysis of the epidemiological characteristics of the 2022 Mpox outbreaks

Background In 2022, there were outbreaks of Mpox where the disease is not endemic. We summarized published full-text epidemiological data from the outbreaks. Methods A global evidence review (protocol: osf.io/j3kb7) with systematic literature search up to February 09, 2023. We focused on experimental/observational studies of laboratory confirmed Mpox, excluding case reports and case series of < 5 cases. Epidemiological data were pooled using an inverse variance, random-effects model, and pooled estimates presented with associated 95% confidence intervals. Results We included 66 studies. Mean incubation period was 7.8 days (6.6–9.0 days, 8 studies: 560 cases), reproductive number 1.8 (1.7–1.9, 6 studies), mean duration from symptom onset to diagnosis 5.8 days (4.8–6.8 days, 4 studies: 982 cases), mean symptom duration 17.5 days (14.7–20.2 days, 3 studies: 292 cases), mean serial interval 8.5 days (7.3–9.9 days, 1 study), hospitalisation 6% (4–9%, 26 studies: 5339 cases), and vaccine effectiveness 78% (65–91%, 3 studies: 953 cases). Highly relevant clinical manifestations were pleomorphic skin lesions 82% (68–94%, 26 studies: 4093 cases), anogenital lesions 64% (51–77%, 9 studies: 10,398 cases), fever 54% (50–57%, 52 studies: 25,992 cases), and lymphadenopathy 51% (46–57%, 42 studies: 17,803 cases), with cases mostly men who have sex with men (MSM). Possibly relevant manifestations were perianal lesions, fatigue, asthenia, myalgia, and headache. Conclusions The 2022 Mpox outbreaks presented with sex-related clinical manifestations and were mostly reported among MSM.