Background: The duration of protection after hepatitis B vaccination of infants is unknown.
Methods: We determined antibody to hepatitis B surface antigen (anti-HBs) at 4–13 years of age in 363 low risk children who had been vaccinated starting at birth with hepatitis B vaccine. Those with nonprotective titers (<10 mIU/mL) received a booster dose. We similarly followed 16 children of hepatitis B surface antigen (HBsAg)-positive mothers.
Results: Of low risk infants receiving a plasma-derived vaccine, 41% (42 of 102) of those whose primary response was unknown and 24% (4 of 17) who had initially responded retained protective titers (≥10 mIU/mL) of anti-HBs at 9 and 13 years, respectively. Of those who did not have protective antibody titers, 61% (33 of 54) and 67% (8 of 12), respectively, responded to a booster dose. In children of HBsAg-positive mothers, 31% retained protective anti-HBs at 12 years, and 90% (9 of 10) with nonprotective titers responded to a booster. In low risk children initially receiving a recombinant vaccine, 12.5% (26 of 208) and none (0 of 36) retained protective anti-HBs titers at 5 and 7 years of age, respectively. Of those who did not have protective titers, 90% (120 of 134) and 91% (32 of 35), respectively, responded to a booster.
Conclusions: Anti-HBs disappeared by 5 years of age in most children who were vaccinated with hepatitis B vaccine from birth. Although most children showed immunologic memory, one-third failed to demonstrate an anamnestic response to a booster dose. Additional long term studies of low risk infants are needed to determine duration of protection and the necessity for or timing of booster doses.
From the *Arctic Investigations Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, and the †Viral Hepatitis Program, Alaska Native Tribal Health Consortium, Anchorage, AK
Accepted for publication March 11, 2004.
Supported in part by Merck Research Laboratories (study 1) and a memorandum of agreement between CDC and the Alaska Native Medical Center (study 2).
Address for reprints: Lisa R. Bulkow, Arctic Investigations Program, Centers for Disease Control and Prevention, 4055 Tudor Centre Drive, Anchorage, AK 99508. Fax 907-729-3429; E-mail firstname.lastname@example.org