How should I manage an infant of an HBsAg-positive mother who tests negative for anti-HBs after 3 properly spaced doses of vaccine?

HBsAg-negative infants with anti-HBs levels 10 mIU/mL or higher are protected and need no further medical management. HBsAg-negative infants with anti-HBs less than 10 mIU/mL should be revaccinated with a single dose of hepatitis B vaccine and receive postvaccination serologic testing 1–2 months later. Infants whose anti-HBs remains less than 10 mIU/mL following single dose revaccination should receive 2 additional doses of HepB to complete the second series, followed by postvaccination serologic testing 1–2 months after the final dose.

Based on clinical circumstances or family preference, HBsAg-negative infants with anti-HBs less than 10 mIU/mL may instead be revaccinated with a second, complete 3-dose series, followed by postvaccination serologic testing performed 1–2 months after the final dose of vaccine.