HBsAg and anti-HBs coexistence in patients with HBV in acute and chronic phases

HBsAg and anti-HBs coexistence represents an unusual serological pattern in hepatitis B virus (HBV) infection. However, its natural course remains unclear. This study investigated the occurrence of this serological pattern in patients with HBV in acute and chronic phases and estimated the associated risks. Of the 215 adult patients diagnosed with acute-phase HBV, 19 (8.84 %) cases demonstrated HBsAg and anti-HBs coexistence. In the chronic phase, 54 new cases of HBsAg and anti-HBs coexistence were identified during a median follow-up of 14 months (interquartile range: 14-28) among 4593 HBsAg-positive patients. The average annual incidence of coexistence was 1.41 % ± 0.28 %. The cumulative risk of HBsAg and anti-HBs coexistence in chronic phase patients was higher in those aged ≥ 50 years (risk ratio [RR]: 1.79, 95 % confidence interval [CI]: 1.04-3.09, P = 0.035), with positive HBeAg (RR: 3.43, 95 % CI: 1.91-6.19, P < 0.001), baseline alanine transaminase abnormalities (RR: 3.62, 95 % CI: 1.93-6.79, P < 0.001), and higher HBV DNA levels (RR: 1.97, 95 % CI: 1.12-3.49, P = 0.017). The quasispecies heterogeneity of the "a" determinant mutation demonstrated no significant change during the occurrence of coexistence with HBsAg and anti-HBs in HBV infection. Therefore, HBsAg and anti-HBs coexistence may be the intermediate process in the natural history of HBV infection, unrelated to "a" determinant mutation but associated with the disease phase.