Changes of hepatitis B markers among young adults in a hepatitis B virus endemic area: a follow up study on medical students.

To elucidate the hepatitis B virus (HBV) infection status of teenagers, to observe changes of the status of these young adults after long-term follow up, to clarify the HBV replication activity of young HBsAg carriers, and to understand the anti-HBs titer of those immune to HBV-infection, a comparison between two health examinations at a 5-or 6-year interval was conducted among 132 medical students. Their ages were 19.1 +/- 0.9 (mean +/- SD). There were 19 (14.4%) HBsAg carriers, 57 (43.2%) immune to HBV infection, and 56 (42.4%) susceptible to HBV. All 19 HBsAg positive carriers were still in carrier status in the second examination. Twelve (63.1%) of the HBV carriers had already HBeAg negative seroconversion before the age of 25. And two carriers might be in the late e seroconversion phase. One susceptible student had a subclinical HBV infection during his university life, with an incidence of HBV infection of 0.47% (1/213) per person-year. Nine (11%) of 82 HBV-immune students had lower anti-HBs concentrations. Six of the 9 students were immunized by natural infection. Anamnestic response developed after booster vaccination. This study shows that these young adults have an HBsAg-carrier rate similar to the general adult population in Taiwan. However, HBeAg seroconversion occurs more often and earlier in this particular population than previous reports have indicated. Moreover, only 24 (40%) susceptible subjects received HBV vaccination after the first recommendation and it is necessary to be more forceful in recommending prompt vaccination.