An asymptomatic blood donor screens positive for anti-HBc (IgG) alone: HBsAg negative, anti-HBs negative, anti-HBe negative, HBV DNA undetectable by PCR. He recalls completing the recombinant hepatitis B vaccine series years ago. The most appropriate interpretation is:

• A This pattern is expected after successful vaccination
• B He has chronic hepatitis B in the immunotolerant phase
• C He has acute hepatitis B in the window period and must be deferred permanently
• D The result most likely reflects past exposure with loss of detectable markers, though false-positive anti-HBc is possible ✓

Explanation

Isolated anti-HBc positivity means prior exposure to whole virus, never vaccination, because the recombinant vaccine contains only HBsAg. With undetectable DNA and no HBsAg, the usual explanation is remote resolved infection in which anti-HBs has waned below detection, although a low-level false-positive anti-HBc is well described. Vaccinated individuals develop anti-HBs alone. Acute window-period infection would show anti-HBc IgM and typically detectable HBV DNA.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.