722. Persistence of Immunity After Two-dose Inactivated Hepatitis A Vaccination of Infants and Young Children According to Maternal Antibody to Hepatitis A Virus Status: 10-year Follow-up
Session: Poster Abstract Session: Vaccine Studies, Adjuvants, and Discovery
Friday, October 21, 2011
Room: Poster Hall B1
Background:

Persistence of immunity to response from hepatitis A vaccine administered in children under 2 years of age is unknown and passively transferred maternal antibodies to hepatitis A virus (maternal anti-HAV) may lower infant immune response. 

Methods: 

Infants and young children (N=197) were recruited at the Alaska Native Medical Center in Anchorage and randomized into three groups to receive a two dose of hepatitis A vaccine (HAVRIX, GlaxoSmithKline; 720 EL.U. in 0.5 ml): group 1 at 6 and 12 months, group 2 at 12 and 18 months, and group 3 at 15 and 21 months of age; within groups, infants were randomized by maternal anti-HAV status. Anti-HAV levels were measured at 1 and 6 months, and at 3, 5, 7 and 10 years after second dose of hepatitis A vaccination. 

Results:

Children in all groups had evidence of seroprotection (≥10mIU/mL) at 1 month after dose 2.  10 years after the 2nd dose, all children retained seroprotective anti-HAV levels except for only 6% and 9% of children in group 1 born to anti-HAV negative and anti-HAV positive mothers, respectively.  At 10 years, children born to anti-HAV-negative mothers in Group 3 had highest geometric mean concentration (GMC) (100 mIU/mL, 95% CI: 66-151) and children born to anti-HAV-positive mothers in Group 1 had lowest GMC (33 mIU/mL, 95% CI: 21-52).  In each group anti-HAV levels through 10 years of age correlated with initial peak anti-HAV levels (tested at 1 month after second dose).

Conclusion:

The immunity induced by hepatitis A vaccine given to children < 2 years of age persists for at least 10 years regardless of presence of maternal anti-HAV.


Subject Category: I. Adult and Pediatric Vaccines

Umid M. Sharapov, MD, MSc1, Lisa Bulkow, MS2, Susan Negus, RN3, Philip R. Spradling, MD1, Chriss Homan, BS3, Jan Drobeniuc, MD, PhD1, Michael Bruce, MD, MPH2, Saleem Kamili, PhD1, Dale Hu, MD, MPH1 and Brian McMahon, MD2,4, (1)Division of Viral Hepatitis, CDC, Atlanta, GA, (2)Arctic Investigations Program, CDC, Anchorage, AK, (3)Alaska Native Medical Center, Anchorage, AK, (4)Alaska Native Tribal Health Consortium, Anchorage, AK

Disclosures:

U. M. Sharapov, None

L. Bulkow, None

S. Negus, None

P. R. Spradling, None

C. Homan, None

J. Drobeniuc, None

M. Bruce, None

S. Kamili, None

D. Hu, None

B. McMahon, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.