Surveillance of Mpox Cases Attending Sexual Health Services in England (SOMASS): Design, implementation and initial findings from the SOMASS data collection tool, 2022

Objectives We aimed to design and implement a data collection tool to support the 2022 mpox (monkeypox) outbreak, and to describe clinical and epidemiological data from individuals with mpox attending sexual health services (SHSs) in England. Methods The UK Health Security Agency and the British Association for Sexual Health and HIV established the Surveillance of Mpox Cases Attending Sexual Health Services in England (SOMASS) system. Descriptive data were collected via a secure web-based data collection tool, completed by SHS clinicians following consultation with individuals with suspected mpox. Data were collected on patient demographics, clinical presentation and severity, exposures and behavioural characteristics. Results As of 17 November 2022, 276 SOMASS responses were submitted from 31 SHSs in England. Where recorded, most (245 of 261; 94%) individuals identified as gay, bisexual or men who have sex with men (GBMSM), of whom two-thirds were HIV negative (170 of 257; 66%) and taking HIV pre-exposure prophylaxis (87 of 140; 62%), with a median age of 37 years (IQR: 30-43). Where known, thirty-nine per cent (63 of 161) had a concurrent sexually transmitted infection (STI) at the time of their mpox diagnosis. For 46% of individuals (127 of 276), dermatological lesions were the initial symptom. Lesions were mostly asymmetrical and polymorphic, predominately affecting the genital area and perianal areas. Nine per cent (24 of 276) of individuals were hospitalised. We report an association between receptive anal intercourse among GBMSM and proctitis (27 of 115; 24% vs 7 of 130; 5%; p<0.0001), and the presence of perianal lesions as the primary lesion site (46 of 115; 40% vs 25 of 130; 19%; p=0.0003). Conclusions We demonstrate multidisciplinary and responsive working to develop a robust data collection tool, which improved surveillance and strengthened the knowledge base. The SOMASS tool will allow data collection if mpox resurges in England. The model for developing the tool can be adapted to facilitate the preparedness and response to future STI outbreaks.