Evidence on mpox clade Ia and clade Ib: A rapid research needs appraisal.
Spasenoska D., Araya N., de Swart M., Henschke N., Harriss E., Tam G., Patrick-Nwosu A., Moetlediwa M., Ndlovu M., Ntamo Y., Probyn K., Steinke S., Ashley L., Cheng V., Villanueva G., Harris T., Ndwandwe D., Turtle L., Carville S., Norton A., Sigfrid L.
OBJECTIVES: The emergence of a new mpox sub-clade Ib and changes in transmission pattern are of concern. To inform strategies to protect populations and improve outcomes, we implemented a rapid research needs appraisal (RRNA) to identify existing evidence on mpox clade I. METHODS: We searched Embase, MEDLINE, Scopus, and grey literature to 11 February 2025 for human mpox clade I studies. RESULTS: Of 79 studies identified, 2.5% (2/79) were interventional, 97.4% (77/79) observational, presenting data on 59,183 mpox cases. Most (57/79) focused on clade Ia, 16/79 clade Ib, and 6/79 unspecified sub-clade I. 90.8% were set in Africa. Studies focused on clinical characteristics (n = 55), transmission (n = 23), risk factors for disease/severe disease (n = 13), diagnostics (n = 9), social/behavioural factors (n = 6), immune response/seroprevalence (n = 5), and vaccine/treatments (n = 4). Symptoms and complications were similar for both sub-clades. Three studies reported foetal death in 8/12-8/14 pregnant women infected with clade Ib and in 3/4 of women with clade Ia. The pooled case fatality rate (CFR) was 6% (95% CI 3% to 8%) in clade Ia studies and 1% (95% CI 0% to 1%) in clade Ib studies. There were no studies on effectiveness of prevention, treatment, risk of asymptomatic infection, or immune protection over time. CONCLUSION: The identified evidence-gaps provide a baseline to inform coordinated research strategies to generate evidence for clinical and public health responses to improve outcomes.