Nucleic Acid Amplification Testing beyond Serology: Analysis of Blood Donor Screening Yield over 7 Years

Background: Nucleic acid testing (NAT) can identify transfusion-transmissible infections (TTIs) during the serological window period and thereby improve blood safety.The study was conducted in Southern Rajasthan, a region with substantial tribal and migratory populations, where epidemiological patterns of TTIs may differ from metropolitan centers.Materials and methods: Retrospective analysis of NAT screening data from January 2019 to December 2025.All donations screened using Mini-Pool (MP) NAT were included.Nucleic acid testing yield was defined as donations that were seronegative (per routine serology) but NAT reactive (i.e., ELISA-/NAT+).Year-wise totals and marker-wise NAT yields [hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV)] were tabulated; overall and marker-specific yields were expressed per 1,00,000 donations.Results: A total of 57,391 donations were screened (2019-2025).Forty-nine (donors) NAT-yield cases were identified (overall NAT yield 85.3/1,00,000 donations).HBV accounted for 39/49 (79.5%).Nucleic acid testing yield persisted across all years, with no year free of NAT-yield detections.Two cases of viral coinfection were identified during the study period.The predominance of HBV NAT results highlights the residual window period and occult HBV burden despite serology.Nucleic acid testing implementation requires integration with robust counseling services and confirmatory testing pathways; cost considerations must account for long-term prevention of chronic infections, not just per-unit testing costs.Conclusions: Over 7 years, NAT provided a sustained incremental detection of TTIs, supporting its continued role in strengthening transfusion safety in HBV-endemic settings.Programmatic decisions on NAT should consider marker distribution, counseling/care pathways, and costeffectiveness in the local context.