Somsak LolekhaBoonyarat WarachitAmporn HirunyachotePiyaporn BowonkiratikachornDavid J. WestGabriele PoerschkeMahidol UniversityHatyai HospitalNakhon Pathom Regional HospitalCharoen Krung Pracharak HospitalMerck Research LaboratoriesMerck & Co., Inc.2018-07-242018-07-242002-11-01Vaccine. Vol.20, No.31-32 (2002), 3739-37430264410X2-s2.0-0036839308https://repository.li.mahidol.ac.th/handle/20.500.14594/20191The primary objective of this study was to estimate the efficacy of a recombinant hepatitis B vaccine (H-B-VAX™II) in preventing chronic hepatitis B infection when given alone without concomitant hepatitis B immune globulin (HBIG) to healthy Thai infants born of HBeAg-positive carrier mothers. The infants received a 0.5ml (5μg HBsAg) intramuscular injection of H-B-VAX™II either at birth, 1, and 6 months of age (Schedule A) or at birth, 1, 2, and 12 months of age (Schedule B). Blood drawings for the determination of hepatitis B virus (HBV) serologic markers were scheduled 4, 9, and 13 months following the initial dose of vaccine. At 13 months, 5 (10%) of 50 infants vaccinated on Schedule A and 7 (14.9%) of 47 infants vaccinated on Schedule B had experienced chronic HBV infection. Based on an expected infection rate in unimmunized infants of either 70 or 90%, the overall efficacy for both schedules combined was estimated to be 82.3% (95% CI: 70.6, 90.6) or 86.2% (95% CI: 77.1, 92.7), respectively. Corresponding schedule-specific estimates were for Schedule A: 85.7% (95% CI: 68.8, 95.3) or 88.9% (95% CI: 75.8, 96.3) and for Schedule B: 78.7% (95% CI: 59.6, 91.1) or 83.4% (95% CI: 68.6, 93.1). These results suggest that in areas of high endemicity, where mothers may not always be screened for HBV infection, routine vaccination of infants at birth with a course of hepatitis B vaccine alone should be highly protective, even for very high-risk infants of HBeAg-positive mothers. © 2002 Elsevier Science Ltd. All rights reserved.Mahidol UniversityImmunology and MicrobiologyMedicineVeterinaryArticleSCOPUS10.1016/S0264-410X(02)00358-4