title: Long-term immunogenicity and efficacy of a reduced dose of plasma-based hepatitis B vaccine in young adults.
abstract: A cohort of seronegative preclinical medical and dental students and another cohort of seronegative national service recruits who were immunized intramuscularly with a reduced dose (10 micrograms) of plasma-based hepatitis B vaccine (Merck, Sharp & Dohme) at the start of the study and at 1 month and 6 months thereafter were followed up for 5 years and 6 years, respectively. Among the medical and dental students, antibody to hepatitis B surface antigen (anti-HBs) ( > or = 10 mlU/ml) was detected in 81% of the vaccinees at the end of the 5-year follow-up and the geometric mean titre (GMT) had dropped from 412.6 mlU/ml one year after completion of vaccination to 174.9 mlU/ml after 5 years. Antibody to hepatitis B core antigen (anti-HBc) was detected in 0.4-1.0% of the vaccinees but none was positive for hepatitis B surface antigen (HBsAg) during the follow-up period. Among the national servicemen, the anti-HBs seroconversion rate and GMT were considerably lower than those of the preclinical medical and dental students. At the end of the 6-year follow-up, 55% of the vaccinees were positive for anti-HBs ( > or = 10 mlU/ml) and the GMT had dropped from 80.7 mlU/ml one year after completion of vaccination to 30.4 mlU/ml after 6 years. Anti-HBc was detected in 8 (2.7%) and transient HBs antigenaemia in 2 (0.7%) of 293 vaccinees after 4 years.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Quarantine and Epidemiology Department, Ministry of the Environment, Singapore.
authors.forename: K T
authors.initials: KT
authors.lastname: Goh
authors.forename: C J
authors.initials: CJ
authors.lastname: Oon
authors.forename: B H
authors.initials: BH
authors.lastname: Heng
authors.forename: G K
authors.initials: GK
authors.lastname: Lim
mesh_terms: D000328:Adult; D015331:Cohort Studies; D006512:Hepatitis B Core Antigens / Q000302:isolation & purification*; D006514:Hepatitis B Surface Antigens / Q000302:isolation & purification*; D017325:Hepatitis B Vaccines / Q000276:immunology*; D006801:Humans; D008889:Military Personnel; D013335:Students, Dental; D013337:Students, Medical; D014761:Viral Hepatitis Vaccines / Q000276:immunology*
chemical_list: D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D014761:Viral Hepatitis Vaccines