title: Seropositivity among Korean Young Adults Approximately 2 Years after a Single-Dose Vaccination against Hepatitis A Virus.
abstract: We previously observed 80.7% seropositivity and a significant interaction between gender and hepatitis A virus (HAV) vaccine type (Havrix vs. Epaxal) on the seropositivity approximately 11 months after single-dose HAV vaccinations in Korean young adults. Our objective was to evaluate seropositivity approximately 2 years after a single-dose HAV vaccination and the influence of demographic characteristics on seropositivity, including the interaction between gender and vaccine type. Seronegative medical school students were randomly vaccinated with Havrix or Epaxal. Based on a total serum anti-HAV antibody titer cutoff of 20 IU/mL, 338 participants (76.0%) of the 445 vaccinees were seropositive 20-25 months after a single-dose HAV vaccination. The seropositive rates were similar after vaccination with Havrix (77.0%) and Epaxal (74.9%). Univariate analysis indicated that female (p = 0.052) and less obese (p < 0.001) participants had a higher seropositive rate, whereas other characteristics such as age, alcohol use, smoking history, vaccine type, and follow-up duration were not associated with seropositivity. Multivariate analysis indicated that women (p = 0.026) and participants with moderate alcohol use (p < 0.001) showed significantly higher seropositive rates than men and participants with no or low alcohol use, respectively. The seropositive rates after vaccination with Havrix and Epaxal were 70.9% and 67.5% in men and 87.7% and 91.3% in women, respectively (p for interaction = 0.304). Compared with the seropositive rate approximately 11 months after vaccination, the seropositive rate decreased substantially only in men in the Havrix group (11.0% points), and consequently, the interaction between gender and vaccine type disappeared while seropositivity remained high (87.7% and 91.3% in Havrix and Epaxal groups, respectively) among women approximately 2 years after vaccination. Further studies are needed to assess whether the seropositive rate would be maintained in all groups more than 2 years after a single-dose HAV vaccination.
authors.affiliation: Department of Preventive Medicine, Eulji University School of Medicine, Daejeon, Korea.
authors.forename: Yeong-Jun
authors.initials: YJ
authors.lastname: Song
authors.affiliation: Department of Preventive Medicine, Eulji University School of Medicine, Daejeon, Korea.
authors.forename: Jiseun
authors.initials: J
authors.lastname: Lim
authors.affiliation: Department of Preventive Medicine & Public Health, College of Medicine, Kwandong University, Gangneung, Korea.
authors.forename: Woong-Sub
authors.initials: WS
authors.lastname: Park
authors.affiliation: Department of Preventive Medicine, School of Medicine, Inje University, Busan, Korea.
authors.forename: Haesook
authors.initials: H
authors.lastname: Sohn
authors.affiliation: Department of Preventive Medicine, College of Medicine, Konyang University, Daejeon, Korea.
authors.forename: Moo-Sik
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Department of Preventive Medicine, School of Medicine, Keimyung University, Daegu, Korea.
authors.forename: Dong-Hoon
authors.initials: DH
authors.lastname: Shin
authors.affiliation: Department of Preventive Medicine, Institute for Poverty Alleviation & International Development, Yonsei University Wonju College of Medicine, Wonju, Korea.
authors.forename: Chun-Bae
authors.initials: CB
authors.lastname: Kim
authors.affiliation: Department of Preventive Medicine, Medical College Soonchunhyang University, Cheonan, Korea.
authors.forename: Hwasung
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Preventive Medicine, Wonkwang University Medical School, Iksan, Korea.
authors.forename: Gyung-Jae
authors.initials: GJ
authors.lastname: Oh
authors.affiliation: Department of Cancer Control and Policy, Graduate School of Cancer Science and Policy, National Cancer Center, Goyang, Korea.
authors.forename: Moran
authors.initials: M
authors.lastname: Ki
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006506:Hepatitis A / Q000276:immunology*; D035922:Hepatitis A Antibodies / Q000276:immunology; D022362:Hepatitis A Vaccines / Q000276:immunology; D017957:Hepatitis A Virus, Human / Q000276:immunology*; D006801:Humans; D007117:Immunization, Secondary / Q000379:methods; D007723:Korea; D008297:Male; D014611:Vaccination / Q000379:methods; D014765:Viral Vaccines / Q000276:immunology*; D055815:Young Adult
chemical_list: D035922:Hepatitis A Antibodies; D022362:Hepatitis A Vaccines; D014765:Viral Vaccines; C530970:epaxal berna