The Course of Anti-HBc Antibodies over Time in Immunocompromised Hosts.

Hepatitis B virus infection results in the appearance of anti-HBc antibodies that normally persist lifelong. We analyzed the course of anti-HBc antibodies overtime, focusing on patients with a permanent loss or fluctuating anti-HBc antibodies. From 120,531 patients tested for anti-HBc antibodies (Architect, Abbott) from January 2006 to December 2020, ≥4 serial values were available in 8098 and permanent or intermittent anti-HBc loss was observed in 139 patients. It was relatively frequent in baseline anti-HBc positive, immunocompromised patients with available serial measurements of anti-HBc overtime (13% of hematologic/oncologic patients, 10% of solid organ transplant recipients, and 6% of HIV patients compared to 3% in patients with other diseases). In the same period, 12,607 samples were tested for HBsAg, anti-HBc antibodies, and HBV DNA-in nine cases we detected HBV DNA with undetectable anti-HBc and HBsAg. In four out of nine cases contamination of the PCR during processing was the likeliest cause, in another four, no further data were available, while in one the HBV DNA was later followed by a temporary anti-HBc seroconversion. In conclusion, permanent or intermittent anti-HBc loss is more common in immunocompromised hosts than in patients with other underlying diseases. Furthermore, anti-HBc and HBsAg assays can be safely used to exclude an active HBV infection, even in immunocompromised hosts.