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Tdap in Pregnancy — USMLE Step 2 CK MCQ

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HardObstetrics & GynecologyTdap in PregnancyUSMLE Step 2 CK

At 28 weeks of pregnancy, a patient is HBsAg positive with HBV DNA 620,000 IU/mL and normal creatinine. Which plan most effectively reduces perinatal transmission?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: A — Give maternal tenofovir and neonatal vaccine plus HBIG at birth

HBV DNA above 200,000 IU/mL is the threshold for maternal antiviral therapy to reduce perinatal transmission; tenofovir is preferred and is started in late pregnancy. The newborn still needs both monovalent hepatitis B vaccine and HBIG promptly at birth because maternal therapy is adjunctive, not a substitute. Maternal vaccination does not treat chronic infection, cesarean delivery alone is not preventive therapy, and delayed infant prophylaxis forfeits its protective effect.

Reference: CDC Clinical Care of Hepatitis B. https://www.cdc.gov/hepatitis-b/hcp/clinical-care/index.html