Changing hepatitis A epidemiology among Hong Kong Chinese adolescents: what are the implications?

Objective: To study the sero-epidemiology of hepatitis A virus (HAV) among adolescents in Hong Kong and analyse the changing patterns of the infection rates. Design: Cross sectional study. Setting: Secondary school students. Subjects: One thousand, five hundred and eighty students were randomly sele cted from 12 schools in four regions of Hong Kong. Main outcome measures: Anti-HAV status. Results: The overall prevalence of anti-HAV is 7%. The sere-prevalence for age group 11-20 y has fallen compared with 44.8% in 1978, 17.1% in 1987 and 11.2% in 1989. Those adolescents born in mainland China, who are frequent travellers and had a longer period of residence in mainland China were show n to have a higher prevalence of anti-HAV. Conclusion: The changing epidemiology of HAV indicates that Hong Kong will have a large proportion of susceptible young adults. Because of its geograp hic situation and import of most its food supplies from less developed coun tries, for epidemiological purposes the inhabitants can be compared to west ern travellers staying in a five star hotel in a less developed country. Th e risk of an outbreak of HAV is to be expected. Vaccination has the potenti al to serve as an effective prevention for adolescents living in countries whose circumstances are similar to Hong Kong.