Should WHO-prequalified antigen-antibody fourth-generation rapid diagnostic tests be used to detect acute HIV infection? A systematic review and meta-analysis of diagnostic performance

IntroductionDiagnostics have become the fundamental backbone of HIV prevention, treatment and long-term retention in care, and are critical to achieving the 95-95-95 UNAIDS targets. To effectively reach underserved and remote populations, diagnostic technologies must be cost-effective, robust, user-friendly and suitable for settings with limited infrastructure. Among available testing modalities, rapid diagnostic tests (RDTs) play a central role in expanding HIV testing coverage. Earlier generations of RDTs were limited by their inability to detect acute HIV, with limited ability to detect p24 antigen (Ag), an early marker of HIV infection, which is expected to shorten the diagnostic window to two-to-three weeks. The introduction of fourth-generation RDTs, which detects both chronic and acute HIV infection through p24 Ag detection, was designed to ensure that the traditional diagnostic window of two-to-three months is shortened to approximately two-to-three weeks. However, integrating these assays into existing testing algorithms requires clear evidence that they meet high standards of quality and performance. This systematic review aims to assess the performance of WHO-prequalified fourth-generation Ag/Ab RDTs. MethodsWe performed a systematic search across six databases to identify studies evaluating Ag/Ab RDTs against laboratory reference standards in individuals aged 12 years and older, spanning 1 January 2010 to 31 December 2025. Outcomes were limited to measures of diagnostic accuracy. A meta-analysis focusing exclusively on WHO-prequalified fourth-generation RDTs was performed using a bivariate random-effect model. Results1,932 records were screened, of which 31 diagnostic accuracy studies from 19 countries were included. 15 studies used US-only approved products, 12 used WHO-prequalified products and four used commercially discontinued products. The pooled sensitivity of WHO-prequalified Ag/Ab RDTs for acute HIV infection (AHI) was 94% (95% CI: 86%-99%). An RNA threshold of [≥] 1,000,000 copies/mL was used as a proxy for high viraemia and used as a cut-off for the following analyses. The cut-off based analysis is considered more suited to decision-making, as it focuses on cases most likely to be associated with higher viraemia and greater potential for detection during the p24 Ag window. When using enzyme immunoassay (EIA) as the reference standard, the pooled p24 Ag sensitivity was 76% (95% CI: 62%-88%), and the pooled p24 Ag sensitivity when using nucleic acid amplification test (NAAT) as the reference standard was 75% (95% CI: 41%-97%). In the general population, the pooled sensitivity for p24 antigen detection was 77% (95% CI: 60%-92%). Amongst risk populations, only three studies had available raw data, and the pooled sensitivity was 62% (95% CI: 10%-97%). In plasma and serum specimens, pooled p24 Ag sensitivity was 74% (95% CI: 57%-88). DiscussionCollectively, these findings indicate that WHO-prequalified fourth-generation Ag/Ab RDTs can function as a scalable frontline screening tool, particularly in low- and middle-income countries, while offering incremental holistic detection through p24 Ag. Their effective deployment, however, depends on maintaining standard algorithm safeguards, including repeat testing and targeted laboratory referral when acute infection is suspected. ConclusionsResults from this meta-analysis support the use of WHO-prequalified fourth-generation Ag/Ab RDTs for general population screening. From a programmatic perspective, the added value of WHO-prequalified fourth-generation RDTs lies in their ability to combine rapid, decentralized access to testing, with incremental yet impactful improvements in holistic detection.