A mathematical approach to estimate the efficacy of individual‐donation and minipool nucleic acid amplification test options in preventing transmission risk by window period and occult hepatitis B virus infections

Background Sensitivity data from a head‐to‐head comparison study in S outh A frica were used to compare the efficacy of the U ltrio P lus assay in individual‐donation ( ID ) and minipool ( MP )4 and MP 8 formats with that of T aq S creen MP 6 in preventing hepatitis B virus ( HBV ) transmission risk. Study Design and Methods The replicate nucleic acid test ( NAT ) results on 106 HBV NAT ( U ltrio)‐yield samples and 29 HBV   DNA ( U ltrio)‐negative, hepatitis B surface antigen ( HBsAg) ‐positive samples were used to determine the viral load in copies/mL against the E urohep HBV standard by probit analysis. Random viral load distributions were established in 32 pre‐ HBsAg window period ( WP ), 15 post‐ HBsAg WP , and 56 occult HBV infection ( OBI ) donations. Regression analysis of log viral load and P oisson distribution statistics of infectious HBV particles in blood components was used to predict infectivity and efficacy of NAT options in removing HBV transmission risk. Results For red blood cell transfusions (20 mL of plasma), the modeling predicted an U ltrio P lus ID ‐ NAT efficacy of 68 and 83% in removing WP and (antibody to hepatitis B surface antigen–negative) OBI transmission risk, respectively, compared to 52 and 49% by T aq S creen MP 6. For 200 mL of fresh‐frozen plasma the estimated efficacy levels by these ID ‐ and MP 6‐ NAT options reduced to 57 and 44% for WP and to 67 and 34% for OBI donations, respectively. Conclusion The efficacy of the currently available commercial NAT systems in reducing HBV transmission risk is mainly driven by the pool size and the transfusion plasma volume. The modeled OBI transmission risk and NAT efficacy levels were in line with those recently reported in three lookback studies and give more insight in the incremental safety provided by HBsAg and antibody to hepatitis B core antigen testing of ID ‐ NAT screened blood.