D O N O R I NOFREICGTIINOAULS DA IRSTEI AC SL EE T E S T I N G The yield of universal antibody to hepatitis B core antigen donor screening in the Netherlands, a hepatitis B virus low-endemic country Thijs J. van de Laar,1,2 Tanneke Marijt-van der Kreek,3 Marijke W. Molenaar-de Backer,1,2 Boris M. Hogema,1,2 and Hans L. Zaaijer1,4

BACKGROUND: In the Netherlands, universal antibody to hepatitis B core antigen (anti-HBc) donor screening was introduced in July 2011 to intercept potentially infectious donations slipping through hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA minipool screening (HBV DNA MP6). STUDY DESIGN AND METHODS: The yield and donor loss were evaluated after the first 2 years of universal anti-HBc donor screening. A total of 382,173 donors were tested for anti-HBc and, if positive, for antibody to HBsAg (anti-HBs). Anti-HBc–reactive donors with antiHBs of less than 200 IU/L were deferred, but repeat donors were allowed retesting after 6 months if antiHBs was less than 10 IU/mL. Anti-HBc false positivity was estimated using the crude anti-HBc signal, family name–based ethnicity scoring, and donor follow-up. RESULTS: Anti-HBc screening identified 13 confirmed or potential HBsAg- and HBV DNA MP6–negative recent HBV infections. In addition, 820 anti-HBc– reactive donors with low anti-HBs titers (1000 Negative Negative >1000 Negative Negative 44 Negative Negative 20 443 985 37 177 128 437 112 277

Core IgM NT Positive Positive NT Positive Positive NT Positive NT Positive NT NT NT NT NT Negative Negative NT Negative Negative NT Negative Negative NT Negative NT Negative NT NT NT NT

HBV DNA individual NT Positive Positive NT Negative Negative NT Negative NT Negative NT NT NT NT NT Negative Negative NT Negative Negative NT Negative Negative NT Negative NT Negative NT NT NT NT

Imputability Confirmed

Probable

Probable Probable Probable Possible† Possible†

Possible†

Possible†

Possible Possible Possible Possible

* The first anti-HBc–reactive visit is Day 0. † If not vaccinated. NT = not tested.

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TRANSFUSION

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Volume 55, June 2015 TRANSFUSION 1209

VAN DE LAAR ET AL.

(temporary) deferral of 1583 donors. First-time anti-HBc screening of new and repeat donors accounted for 1178 (74%) deferrals, and follow-up screening added 405 (26%) deferrals. Of the 1583 donors deferred, 939 (59%) directly faced permanently deferral, and 644 (41%) were allowed to return for retesting. This two-strike policy proved only partially successful: 188 of 644 (29%) donors reentered the pool of eligible donors upon retesting.

Loss of new donors At their first visit to the blood bank, 529 new donors tested anti-HBc reactive without detectable HBsAg or HBV DNA using minipool screening. Undetectable (n = 89) or low (n = 167) anti-HBs titers resulted in an anti-HBc deferral rate of 256 of 70,914 (0.36%) among new donors (Fig. 2). The anti-HBc deferral rate of new donors remained stable over time and varied between 0.24 and 0.43% per trimester.

Loss of repeat donors: first-time anti-HBc screening At first-time anti-HBc screening, 2331 of 311,259 (0.75%) repeat donors tested anti-HBc positive (Fig. 2). Of them, 567 of 311,259 (0.18%) donors were permanently deferred as a result of low anti-HBs titers (