Prevalence of Hepatitis B Virus Seromarkers in Young Adults Vaccinated at Birth; Impact on the Epidemiology of Hepatitis B Infection in Iran

Background: the epidemiological impact and the duration of protection provided by infant hepatitis b (hb) vaccination are unknown. objectives: this study was designed to determine the hepatitis b virus (hbv) infection seromarkers in young adults who have been vaccinated against hbv as the first group of iranian neonates during 1993 and 1994. patients and methods: we recruited 510 young adults with a history of complete hb vaccination at birth. hbv seromarkers (hb surface antigen (hbs ag), antibody against hbs ag (anti-hbs), and antibody against hb core antigen (anti-hbc) were measured using elisa method. anti-hbs titers ≥ 10 iu/l were considered protective and titers more than 300 iu/l were indicative of a natural boosting. positive results for anti-hbc and hbs ag were considered as breakthrough infection and possible vaccine failure, respectively. the history of acute symptomatic clinical hepatitis was also investigated. results: anti-hbs seropositivity rate was detected in 224 of 510 [95% ci: 39-47] young adults. breakthrough infection (positive sera for anti-hbc without chronic infection) was observed in 18 [95% ci: 2.5-3.5] subjects. there were neither hbs ag positive results nor symptomatic hepatitis cases. conclusions: the study results indicated that the neonatal hbv immunization induced a long-term protection against hbv and was very efficacious in reducing chronic hbv infection rate in vaccinated young adults in iran.