Efficacy of hepatitis B sero-vaccination in newborns of African HBsAg positive mothers.

BACKGROUND Maternal-infant transmission of hepatitis B virus (HBV) during birth carries a high risk of chronic HBV infection in infants. Appropriate neonatal prophylaxis is effective in preventing perinatal transmission of HBV. The purpose of this study was to evaluate the protective efficacy of anti-HBV sero-vaccination in newborns of HBsAg positive mothers from Mayotte, French island in the Mozambican canal. PATIENTS AND METHODS One-hundred newborns of HBsAg positive mothers were identified retrospectively on the basis of hospital medical record and hepatitis B immune globulin (HBIG) prescriptions review from 1994 to 2007. To determine the rate of protective efficacy of neonatal prophylaxis defined by anti HBs antibodies >10 IU/mL with negative HBsAg, anti HBc and HBV DNA testing, HBV serological markers were performed in vaccinated children. RESULTS Eighty-three of 100 newborns (83%) were given a complete sero-vaccination. Maternal HBe Ag status at delivery (available in 93%) was positive in 56 (60%) of cases and HBV viral load (available in 57%) was <5 logIU/mL, between 5 and 7 logsIU/mL and >7 logsIU/mL in 23 (40.4%), 12 (21%) and 22 (38.6%), respectively. HBV markers in all children at a median age of 5 years [IQR 2-8] showed that 76% were protected with anti HBs >10 IU/mL, despite incomplete sero-vaccination in 12 infants; 6% of infants had anti-HBs and anti-HBc positivity with undetectable HBV DNA, 1% had isolated anti HBc while 14% were seronegative. Only 3% had evidence of immunoprophylaxis failure: 1 infant was HBsAg carrier and 2 had detectable HBV DNA without HBsAg (occult HBV infection). The only factor associated with sustained protective efficacy was on time serological control performed within one year of life, whereas maternal age, HBeAg status and HBV viral load on delivery were not. CONCLUSION The anti-HBV sero-vaccination of newborns of HBsAg-positive mothers is fairly done in Mayotte and allows a high protection of mother-to-child transmission in a mean endemic area with fair safety. Screening of sero-vaccination failures has to be reinforced in order either to revaccinate or to treat infected children.