Hepatitis A vaccination of infants: effect of maternal antibody status on antibody persistence and response to a booster dose.
BACKGROUND
Infants with passively transferred maternal antibody (PMA) to hepatitis A virus (HAV) have lower concentrations of antibody to HAV (anti-HAV) after vaccination. We examined the effect of PMA on persistence of anti-HAV and on immune memory.


METHODS
We measured anti-HAV concentrations of 6-year-old children who had responded to a three dose hepatitis A vaccine series at ages 2, 4 and 6 months. Group 1 children were born to anti-HAV-negative women; Group 2 children had anti-HAV-positive mothers and PMA at 2 months of age. Children without detectable antibody at 6-year follow-up were offered a booster dose [360 enzyme-linked immunosorbent units (ELU)]. An anamnestic response was defined as a postbooster anti-HAV concentration of > or =400 mIU/ml.


RESULTS
At follow-up, before the booster dose, Group 1 subjects had a higher geometric mean concentration (50 mIU/ml vs.18 mIU/ml, P = 0.007), and a larger proportion retained seroprotective concentrations of anti-HAV [21 of 31 (68%) vs.4 of 17 (24%)] compared with Group 2 subjects. The two stage antibody decline curves for the two groups from 8 months old to follow-up testing were parallel. An anamnestic response occurred in all (5 of 5) Group 1 and 67% (4 of 6) of Group 2 children. The geometric mean antibody concentrations after the booster were 1102 and 406 mIU/ml for Groups 1 and 2, respectively (P = 0.10).


CONCLUSIONS
Infants with PMA who receive hepatitis A vaccine have significantly lower concentrations of anti-HAV 6 years later than infants with no PMA who receive hepatitis A vaccine. Immune memory may remain functional despite these lower anti-HAV concentrations.
Fiore
Anthony E
AE
Division of Viral Hepatitis, Centers for Disease Control and Prevention, Mailstop G37, 1600 Clifton Road, Atlanta, GA 30333, USA. afiore@cdc.gov
Shapiro
Craig N
CN
Sabin
Keith
K
Labonte
Kathy
K
Darling
Karen
K
Culver
David
D
Bell
Beth P
BP
Margolis
Harold S
HS
D000328:Adult; D002648:Child; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006506:Hepatitis A / Q000276:immunology* / Q000517:prevention & control*; D022362:Hepatitis A Vaccines / Q000008:administration & dosage*; D006510:Hepatitis B Antibodies / Q000032:analysis / Q000097:blood*; D006801:Humans; D007109:Immunity / Q000502:physiology*; D007112:Immunity, Maternally-Acquired; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007223:Infant; D008297:Male; D011247:Pregnancy; D012680:Sensitivity and Specificity; D013997:Time Factors; D014611:Vaccination / Q000379:methods*
D022362:Hepatitis A Vaccines; D006510:Hepatitis B Antibodies