Long-term protection following a primary series of hepatitis B vaccine in Alaska Native children and adults.

BACKGROUND

Vaccination is effective at preventing chronic HBV infection and its complications, but the duration of protection and need for booster doses have not been determined.

METHODS

We administered a 3-dose primary series of plasma-derived hepatitis B vaccine to Alaska Native persons aged 6 months or above who resided in an HBV-endemic area of western Alaska. Persons with antibody to hepatitis B surface antigen (anti-HBs) ≥10 milli-international units per milliliter (mIU/mL) at 6 months after series completion were followed through 41 years after vaccination. Beginning at 22 years, participants with anti-HBs <10 mIU/mL were offered a booster dose (ie, challenge dose) of recombinant hepatitis B vaccine and retested 4 weeks later as a surrogate for immune memory. Combining these immune-memory data with a survival model estimating anti-HBs persistence, we estimated the overall proportion with serologic evidence of protection at 22, 30, 35, and 41 years. We also described breakthrough hepatitis B infections.

RESULTS

During 1981-1982, 1351 persons completed the hepatitis B vaccine primary series and had anti-HBs ≥10 mIU/mL at 6 months after vaccination; median age at enrollment was 13 years (range: 0.5-77). The overall proportion with serologic evidence of protection was 95% at 22 years, 95% at 30 years, 88% at 35 years, and 91% at 41 years after vaccination. At 41 years, 32% had circulating anti-HBs ≥10 mIU/mL, and 59% had immune memory. During 41 years of follow-up, 16 (1%) persons had evidence of a breakthrough infection; none developed chronic hepatitis B.

CONCLUSIONS

We found serologic evidence of protection among Alaska Native persons 41 years after primary hepatitis B vaccination. Our findings support the recommendation that booster doses are not needed in endemic areas.