By C. Vidyashanker, MD
DELHI, India (Reuters Health) Oct 01 - Preterm infants from areas endemic
for hepatitis B may need a four-dose schedule instead of the currently
recommended three doses of hepatitis B vaccine, researchers from India report.
Dr. N. K. Arora and colleagues from the All India Institute of Medical
Sciences in Delhi studied the response to hepatitis B vaccine in 60 term
infants with intrauterine growth retardation and 82 premature infants. Infants
born before 37 weeks of gestation were considered premature, while those born
at term with weights below the 10th percentile were considered to have
intrauterine growth retardation (term-IUGR).
Infants in both groups were administered four doses of a recombinant
hepatitis B vaccine, with the first dose at birth and subsequently at 6, 10
and 14 weeks of age. Anti-hepatitis B immunoglobulin G (IgG) levels were
measured before each dose of vaccine and then after the final dose. Antibody
levels of at least mIU/mL were considered protective and a titer of at least
100mIU/ml was deemed a high response.
Dr. Arora and colleagues report in the September issue of Acta Paediatrica
that the number of infants who achieved protective levels of antibodies after
the third dose of vaccine was significantly greater in the term-IUGR group
than in the premature group. This could be due to the immunological immaturity
in the premature neonates, the investigators postulate.
The fourth dose of hepatitis B vaccine, however, produced a significant
improvement in the antibody titers in the preterm infants and resulted in
levels comparable to the term-IUGR group, the researchers report.
The presence of antibodies to hepatitis B in mothers, a common occurrence
in endemic areas, also interfered with the immune response in preterm infants,
the researchers note. This effect was not observed in term-IUGR infants, they
add.
Gestational age is a better predictor of response to hepatitis B
vaccination than birth weights, the researchers write. "Thus in the
immunization schedule starting at birth, an additional dose of hepatitis B
vaccine to preterm infants effectively overcomes immunologic handicaps," Dr.
Arora and colleagues conclude.
Acta Paediatr 2002;91:995-1001.
