Residual risk estimates of transfusion transmissible hepatitis B, hepatitis C and human immunodeficiency virus using nucleic acid testing yield/window period model in an Indian setting.

BACKGROUND: Estimation of residual risk (RR) is necessary to understand status of blood safety with current testing strategies and need to improve it further. These estimates from India are lacking till date. Present study was aimed to estimate RR and incident rate (IR) of transfusion transmitted infectious disease (TTIDs) in Indian setting. STUDY DESIGN AND METHODS: Blood donor demographic data, serological testing results and nucleic acid testing (NAT) screening results were collected retrospectively from January 2015 to June 2017. Mathematical modelling using NAT yield/window period model was done to estimate IR and RR of TTIDs. Data was compared between different groups based on age-group, gender, donation repeatability and type of donor. RESULTS: A total 106 119 blood donors donated 109 441 units with overall TTID reactivity of 2.22%. HBV was most prevalent TTID (1.26%) with RR of 16.1 per million followed by HCV and HIV with RR of 4.4 and 3.1 per million donations, respectively. NAT testing variably reduced RR ranging from 69.4% to 96.1% depending on TTID. Younger, repeat and voluntary donors had significantly lower prevalence of TTIDs compared to older, first time and replacement donors. DISCUSSION: Gaps in the blood safety could be bridged significantly by implementing NAT testing and using quality serological assays. Comparatively high RR despite using quality serological assays and ID-NAT testing highlights need to develop long term strategies to improve blood safety by focusing on improving donor pool by recruiting regular voluntary donors among youth and imparting knowledge of healthy practices.