Evaluation of Influenza A/B, SARS-CoV-2, and RSV Antigen Combo Rapid Test in Under Two Hospitalized Children

Background/Objectives: Next to malaria, respiratory viruses, particularly respiratory syncytial virus (RSV), are responsible for the hospitalization and death of thousands of young children each year in sub-Saharan Africa. During peak seasons, conducting separate tests is time-consuming and distressing. This underscores the need for efficient, rapid multiplexed diagnostic tools. This study evaluated the clinical performance of a lateral flow assay (LFA) based antigen combo rapid diagnostic test (ML Ag Combo RDT, manufactured by MobiLab) that detects RSV, influenza A and B, and SARS-COV-2. Methods: The Allplex rRT-qPCR assay was used as a reference assay to evaluate the clinical performance of the LFA Ag Combo RDT in pediatric hospital settings and performed using 470 nasopharyngeal swab (NPS) specimens from hospitalized children under two with respiratory symptoms. Results: Based on the comparative analysis of the testing results for 470 NPS, the ML Ag Combo RDT demonstrated high sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 90.06%, 98.33%, 93.45%, and 97.38% for RSV, and 71.43%, 100%, 100%, and 92.94% for influenza A/B, respectively. Agreement with the Allplex rRT-qPCR was strong (κ = 0.90 for RSV and 0.82 for Flu A/B), with overall accuracies of 96.60% for RSV and 94.47% for Flu A/B. This was further supported by ROC analysis for aggregated data (RSV and Flu) with an AUC value of 0.925. As expected, in samples with high viral loads (Ct < 20), the Ag Combo RDT achieved 100% sensitivity for RSV and Flu A/B. Sensitivity declined slightly at lower viral loads (Ct > 35). Conclusions: The ML Ag Combo RDT demonstrates high specificity and strong diagnostic accuracy for the detection of RSV and Flu A/B in pediatric hospital settings, where timely diagnosis is critical.