Verification of False Reactivity in <scp>HIV</scp> Rapid Diagnostic Tests and Its Translation Into the Three Tests Algorithm in Cameroon

ABSTRACT Background In a context of HIV seropositivity below 5%, transitioning from a two‐ to a three‐test algorithm is required to secure positive predictive values > 99% for mitigating false reactivity. With Cameroon having 2.7% seroprevalence, we sought to ascertain events of false reactivity from eight WHO‐prequalified HIV rapid diagnostic tests (RDTs) and design suitable combinations for the country three‐test algorithm. Methods A facility‐based study was conducted in July–August 2021 among 172 consenting clients attending health facilities in Yaoundé‐Cameroon. Whole blood was collected and samples characterized in parallel using KHB Diagnostic Kit for HIV (1 + 2) Antibody and INNO‐LIA HIV I/II Ag/Ab to rule out reactive cases. Two lots of each selected RDT were tested simultaneously in quadruplicate on HIV non‐reactive samples and repeated by a different tester. RDTs were considered false positive if any reactivity was detected. Results Following characterization, 25 samples were HIV‐reactive (i.e., ruled out) and 147 non‐reactive. Following random selection, 100 non‐reactive samples tested for false reactivity revealed: 0% (0/100) First Response HIV 1–2‐O Card, 0% (0/100) First Response HIV1 + 2/Syphilis Combo, 0% (0/100) STANDARD Q HIV/Syphilis Combo, 0% (0/99) ONE STEP Anti‐HIV1&2 (one invalid result); 1% (1/100) Determine HIV Early Detect and Bioline HIV/Syphilis Duo, 2% (2/100) Alere Determine HIV‐1/2, 4% (4/100) Rapid Test for Antibody to HIV. Conclusion In the Cameroonian context, HIV false reactivity ranged from 0% to 4% across selected RDTs. Thus, a reliable three‐test algorithm ranks First Response HIV 1–2‐0 Card, First Response HIV1 + 2/Syphilis Combo or STANDARD Q as suitable RDT‐1 to mitigate false‐positive events at the country‐level.