Developing accessible and affordable tests to support mpox immunosurveillance and vaccine studies

Mpox is an ongoing threat to international health security requiring ongoing research. Antibody tests are needed for surveillance studies to understand clinical and sub-clinical transmission risks and respond to outbreaks. With the objective of having a simple and low-cost antibody platform, we developed a laboratory ELISA kit combining four immunodominant mpox proteins to quantify mpox IgG antibody concentration and determine serostatus. The combined assay returns one data point (mpox IgG ratio) per sample. UK serum samples from individuals' post-infection, post-vaccination and those with no known history of mpox infection or vaccination were used to evaluate the assay. The assay effectively discriminated individuals with prior infection or vaccination combined from those without (AUC ·98 [95% CI ·95-1·00], <i>p</i> < .0001), returning a sensitivity and specificity of 95% (95% CI 86·71-98·68 and 89·92-97·78%, respectively). Findings highlight the potential of the ELISA as an accurate and practical solution to aid access to mpox immunodiagnostics and should be evaluated further in endemic settings.