Diagnostic Accuracy of 3 Mpox Lateral Flow Assays for Antigen Detection, Democratic Republic of the Congo and United Kingdom.

Abstract

The ongoing outbreaks of mpox highlight the urgent need for a rapid and low-cost diagnostic test to accurately detect and control this emerging disease. We estimated the analytical sensitivity using viral culture of the monkeypox virus clade IIb lineage B1 and clinical diagnostic performance of 3 antigen detection rapid diagnostic tests (Ag-RDT) by using skin swab samples and upper-respiratory swab samples from mpox patients in the Democratic Republic of the Congo and the United Kingdom. The analytical limit of detection was 1.0 × 10plaque-forming units/mL, fulfilling World Health Organization recommendations. Specificity of the 3 Ag-RDTs was 100%, but sensitivity was estimated at 0.00%-15.79% using skin samples and 0.00% using respiratory samples. None of the 3 Ag-RDTs reached the World Health Organization's target clinical sensitivity, and we do not recommend them as diagnostic or screening tools for suspected mpox cases. Accurate Ag-RDTs for mpox diagnosis remain urgently needed.