From the following, what does the source patient’s hepatitis B serology indicate if HBsAg is negative, anti-HBc is negative, but anti-HBs is positive?

• A. The patient is acutely infected
• B. The patient is immune by means of vaccination
• C. The patient has resolved infection
• D. The patient is susceptible

Answer: (B)

Interpreting hepatitis B serology patterns helps you determine infection status and how immunity was acquired. Here, HBsAg is negative, so there is no active infection. Anti-HBc is negative, indicating there’s no prior exposure to the hepatitis B core antigen. Anti-HBs is positive, showing protective antibody is present. When anti-HBs is positive without anti-HBc, it points to immunity from vaccination rather than natural infection, because vaccination prompts anti-HBs without ever exposing the core antigen. So the best interpretation is immunity by vaccination. If there were anti-HBc positive, especially with a positive anti-HBs, that would suggest resolved infection; if HBsAg were positive, there would be an ongoing infection.