Which HBV serologic pattern distinguishes acute HBV infection from chronic infection?

• A. HBsAg positive with anti-HBc IgM
• B. HBsAg negative and anti-HBs positive
• C. Anti-HBc IgG positive with negative HBsAg
• D. HBsAg positive with anti-HBc IgG only

Answer: (A)

The key to telling acute from chronic hepatitis B is the type of antibody against the core antigen that accompanies active surface antigen. In an acute infection, you see HBsAg present with IgM anti-HBc. The surface antigen shows active infection, and the IgM form of anti-HBc appears early and signals a recent, still-resolving infection. As the infection becomes chronic, the anti-HBc that persists is IgG, not IgM, so chronic HBV typically shows HBsAg with anti-HBc IgG rather than IgM.

Additional patterns help interpret the phase: anti-HBs appears after recovery or vaccination (HBsAg negative, anti-HBs positive). If HBsAg is positive with anti-HBc IgG and no IgM, that points to chronic infection. If HBsAg is negative and anti-HBs positive, the person is immune.