Early infant diagnosis: a pillar in preventing mother-to-child HIV transmission - a narrative review.

Early infant diagnosis (EID) is crucial for preventing and managing mother-to-child transmission of human immunodeficiency virus (HIV). EID enables early detection of HIV in infants born to HIV-positive mothers through nucleic acid testing, particularly polymerase chain reaction (PCR) assays. This narrative review explores EID's role in improving health outcomes for HIV-exposed infants and advances in diagnostic technologies. We also examine implementation challenges, particularly in low-resource settings. A literature review was conducted using PubMed, Scopus, and World Health Organization databases. Peer-reviewed articles from 2000 to 2024 were included based on relevance to EID technologies, implementation barriers, and policy frameworks. Studies focusing on PCR-based methods, point-of-care (POC) testing, and dried blood spot collection were prioritized. Non-English articles and those lacking primary or review data were excluded. EID programs using PCR and POC testing have significantly improved early HIV detection and ART initiation in infants. However, persistent barriers - including high testing costs, limited access to diagnostic infrastructure, delayed result turnaround times, and loss to follow-up - continue to hinder widespread implementation. Integration with maternal health services and use of community-based strategies show promise in bridging these gaps. EID is a cornerstone of pediatric HIV prevention. Strengthening health systems, decentralizing diagnostic services, and adopting innovative implementation strategies are essential to enhance EID coverage and reduce infant HIV-related morbidity and mortality, particularly in high-burden, low-resource settings.