Lack of correlation between HBsAg and HBV DNA levels in blood donors who test positive for HBsAg and anti-HBc: implications for future HBV screening policy

BACKGROUND: Studies showing a significant correlation between hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) deoxyribonucleic acid (DNA) levels have focused on the HBV seroconversion window period. STUDY DESIGN AND METHODS: HBsAg levels relative to HBV DNA results in 200 HBsAg-positive, anti-hepatitis B core antigen (HBc)-reactive blood donations were analyzed using quantitative polymerase chain reaction (PCR) (detection limit 400 copies/mL), two research PCR assays with increasing sensitivities (65 copies/mL and 1.3 copies/mL, respectively), and a quantitative HBsAg assay; HBsAg and HBV DNA levels were correlated with HBV serologic profiles; and the potential for replacing HBsAg screening with nucleic acid testing (NAT) was analyzed. RESULTS: Serologic profiles for over 90 percent of the donor samples were consistent with chronic HBV infection. Correlation between HBsAg and HBV DNA concentrations was weak (correlation coefficient = 0.33). Thirty-six percent (72/200) of donor samples had DNA levels under 400 copies per mL. Retesting of the 72 samples by more sensitive PCR assays showed that 60 out of 200 (30%) were positive by PCR with sensitivity of 65 copies per mL, whereas 6 out of 200 (3%) required PCR sensitivity of 1.3 copies per mL for positivity. Three percent (6/200) were negative by all three NAT assays. CONCLUSIONS: HBV DNA levels in HBsAg-positive, anti-HBc-reactive blood donations can be extremely low. About 6 percent of donations would be negative by current minipool HBV NAT methods. About 3 percent of donations would remain undetected by sensitive single-donor NAT. These results indicate caution in any consideration of dropping HBsAg screening.