Lessons from the European Mpox Outbreak: Strengthening Cohort Research for Future Pandemic Preparedness

Background: Well-designed cohort studies are crucial for pandemic preparedness informing evidence-based infection prevention and treatment strategies. Objectives: Following the 2022 mpox outbreak in Europe, this scoping review critically evaluates the design, implementation, and characteristics of cohort studies focusing on mpox. The aim is to inform recommendations for the Cohort Coordination Board and CoMeCT to enhance cohort study research and improve preparedness. Sources: A comprehensive literature search was conducted in PubMed, Scopus, ClinicalTrials.gov, the EU Clinical Trials Register, and the ECRIN metadata repository up to December 2024. Content: Forty-nine cohorts were identified, encompassing 10,728 individuals with primary or breakthrough mpox and 34,010 individuals without mpox (vaccinated and unvaccinated). The majority of cohorts collected data prospectively (30, 63%) and were multicentre (25, 52%). The primary aims were natural history of mpox (31, 65%); effectiveness of vaccination (15, 31%); and treatment (2, 4%). The most frequent target population was individuals at increased risk of sexually transmitted infection (18, 38%). Follow up of participants varied widely among cohorts. Significant data heterogeneity, stemming from the inconsistent use of standardised data dictionaries, impeded data sharing and meta-analyses. Under-representation of vulnerable populations and limited biobanking further compounded these challenges. Implications: This review underscores critical gaps in the research response during the mpox outbreak. Based on these findings, we propose the following recommendations: (1) Establishing and maintaining "ever-warm" cohorts of high-risk individuals during inter-epidemic periods to enable rapid data collection during future outbreaks; (2) Promoting data interoperability through the development and adoption of standardised data collection tools, and ontologies; (3) Improving the quality of study reporting through strict adherence to relevant guidelines; and (4) Strengthening European and global coordination through the establishment of collaborative research networks. Sustained investment in research infrastructure is essential for a more effective, equitable, and timely public health response to future outbreaks.