If a worker is exposed to HBV and their vaccine response is unknown, which is the correct initial post-exposure action?

• A. Baseline testing for HBV antibodies
• B. Immediate HBV vaccination booster
• C. Post-exposure prophylaxis with hepatitis B immune globulin only
• D. No testing is needed

Answer: (A)

After exposure to hepatitis B, the first step is to determine the worker’s immune status by obtaining baseline HBV serologies, specifically anti-HBs to see if protective antibodies are present and HBsAg to assess current infection. This information guides what prophylaxis, if any, is needed. If anti-HBs is 10 mIU/mL or higher, the worker is considered protected and only routine follow-up is needed. If anti-HBs is below 10 or unknown, the worker is susceptible, and post-exposure prophylaxis should be started with both hepatitis B immune globulin (HBIG) and the hepatitis B vaccine series as soon as possible, ideally within seven days of exposure. Testing first ensures appropriate, targeted protection rather than guessing or delaying care.