Reuters Health Information (2004-04-13): Maternal antibody reduces infant's antibody response to hepatitis A vaccine
Maternal antibody reduces infant's antibody response to hepatitis A vaccine
Last Updated: 2004-04-13 15:15:10 -0400 (Reuters Health)
NEW YORK (Reuters Health) - The presence of maternal antibody to hepatitis A virus (HAV) lowers the antibody response of infants who receive hepatitis A vaccine, according to a report in the March issue of the Journal of Pediatrics.
"The clinical significance of this finding, for example, the effect of these lower antibody concentrations on the duration of protection from vaccination, is not known," Dr. G. William Letson from Centers for Disease Control and Prevention, Atlanta, Georgia told Reuters Health. "Our aim has been to find a dosage and schedule for use in infancy or early childhood that overcomes the interference of passively transferred antibody."
Dr. Letson and colleagues investigated the immunogenicity of hepatitis A vaccine administered to 123 infants beginning at 2 or 8 months of age along with other routinely administered childhood vaccines.
Fifty-one of 52 (98%) of the infants of anti-HAV-negative mothers had protective levels of antibody after the second dose of vaccine (age 4 months), the authors report, compared with 25 of 27 (93%) of infants of anti-HAV-positive mothers receiving the same vaccine schedule.
Only 63% of infants who received HAV vaccine at age 8 months and 10 months had protective levels of antibody at age 8 months, the report indicates.
By age 15 months, all but two infants of anti-HAV-positive mothers had protective levels of antibody, the researchers note, but antibody levels in the infants of anti-HAV-positive mothers remained less than half those seen in the infants of anti-HAV-negative mothers.
None of the infants experienced serious adverse events in association with the vaccines, the results indicate.
"Further studies are needed to determine the appropriate dose and timing of immunization that would achieve a balance between optimal short-term and long-term immunogenicity and integration of hepatitis A vaccine into the childhood immunization schedule," the authors conclude.
"There might be at least a couple of different dosages or schedules for vaccination during infancy, when infants born to immune mothers still have detectable passively transferred antibody, that might overcome the effect of this antibody on response to vaccination," Dr. Letson said.
"Hepatitis A tends to be asymptomatic or minimally symptomatic in children under 5 years of age, and such children can be sources of transmission, making traditional approaches to prevention of hepatitis A outbreaks limited and imperfect," Dr. Letson added. "If the transmission of disease can be interrupted in the first year or two of life, it is possible to nearly or entirely eliminate the disease, since it has no known animal reservoir."
J Pediatr 2004;144:327-332.