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Volume 31, Number 6—June 2025

Research

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

Elie Ishara-Nshombo1Comments to Author , Anushri Somasundaran1, Alessandra Romero-Ramirez, Konstantina Kontogianni, Daniel Mukadi-Bamuleka, Marithé Mukoka-Ntumba, Emile Muhindo-Milonde, Hugues Mirimo-Nguee, Jacob Parkes, Yusra Hussain, Susan Gould, Christopher T. Williams, Dominic Wooding, Juvenal Nkeramahame, Mikaela Watson, Hayley E. Hardwick, Malcolm G. Semple, John Kenneth Baillie, Jake Dunning, Thomas E. Fletcher, Thomas Edwards, Devy M. Emperador, Hugo Kavunga-Membo1, Ana Isabel Cubas-Atienzar1Comments to Author , and ISARIC 4 and C Investigators,2
Author affiliation: Rodolphe Mérieux Laboratory, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo (E. Ishara-Nshombo, D. Mukadi-Bamuleka, M. Mukoka-Ntumba, E. Muhindo-Milonde, H. Mirimo-Nguee, H. Kavunga-Membo); Liverpool School of Tropical Medicine, Liverpool, UK (A. Somasundaran, A. Romero-Ramirez, K. Kontogianni, J. Parkes, Y. Hussain, S. Gould, C.T. Williams, D. Wooding, T.E. Fletcher, T. Edwards, A. Cubas-Atienzar); Royal Liverpool University Hospital NHS Foundation Trust, Liverpool (S. Gould, T.E. Fletcher); Foundation for Innovative New Diagnostics, Geneva, Switzerland (J. Nkeramahame, M. Watson, D.M. Emperador); University of Liverpool, Liverpool (H.E. Hardwick, M.G. Semple); University of Edinburgh, Edinburgh, Scotland, UK (J.K. Baillie); Pandemic Sciences Institute, University of Oxford, Oxford, UK (J. Dunning); Royal Free London NHS Foundation Trust, London, UK (J. Dunning)

Main Article

Table 2

Clinical diagnostic accuracy parameters of 3 MPXV antigen-detecting rapid diagnostic tests from 68 suspected mpox case-patients, the Democratic Republic of the Congo*

Category Skin lesion swab samples, n = 68
 Upper respiratory tract swab samples, n = 68
Ecotest Flowflex Standard Q Ecotest Flowflex Standard Q
True positive 3 3 2 0 0 0
True negative
 49
 49
 49
54
 54
 54
False positive 0 0 0 0 0 0
False negative
 16
 16
 17
14
 14
 14
Specificity, % (95% CI) 100 (92.7–100) 100 (92.7–100) 100 (92.7–100) 100 (93.4–100) 100 (93.4–100) 100 (93.4–100)
Sensitivity, % (95% CI)
 15.79 (5.5–37.6)
 15.79 (5.5–37.6)
 10.53 (2.9–31.4)
0 (0.0–23.2)
 0 (0.0–23.2)
 0 (0.0–23.2)
PPV, % (95% CI) 100 (29.2–100) 100 (29.2–100) 100 (15.8–100) NA NA NA
NPV, % (95% CI)
 75.38 (71.6–78.8)
 75.38 (71.6–78.8)
 74.24 (71.2–77.1)
79.41 (68.4–87.3)
 79.41 (68.4–87.3)
 79.41
(68.4–87.3)
Sensitivity by Ct, % (95% CI)
Ct <20 0 (0.0–79.4), n = 1 100 (20.7–100), n = 1 0 (0.0–79.4), n = 1 NA NA NA
Ct <25 14.29 (2.6–51.3), n = 7 28.57 (8.2–64.1), n = 7 14.29 (2.6–51.3), n = 7 0 (0.0–79.4), n = 1 0 (0.0–79.4), n = 1 0 (0.0–79.4), n = 1
Ct <33 27.27 (9.8–56.7), n = 11 27.27 (9.8–56.7), n = 11 18.18 (5.1–47.7), n = 11 0 (0.0–39.0), n = 6 0 (0.0–39.0), n = 6 0 (0.0–39.0), n = 6
Ct <40 15.79 (5.5–37.6), n = 19 15.79 (5.5–37.6), n = 19 10.53 (2.9–31.4), n = 19 0 (0.0–21.5), n = 14 0 (0.0–21.5), n = 14 0 (0.0–21.5), n = 14

*Tests evaluated: Ecotest, Ecotest Monkeypox Antigen Rapid Test (Assure Tech [Hangzhou] Co., Ltd., https://www.assuretech-product.com); Flowflex, FlowFlex Monkeypox Virus Antigen Rapid Test (ACON Biotech [Hangzhou] Co., Ltd., https://www.aconbio.com); Standard Q, Standard Q Monkeypox Ag Test (SD Biosensor, https://www.sdbiosensor.com). Ct, cycle threshold; MPXV, monkeypox virus; NA, not available; NPV, negative predictive value; PPV, positive predictive value.

Main Article

1These authors contributed equally to this article.

2Members of ISARIC 4C investigator group are listed at the end of this article.

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