Hepatitis a in developed country, the result should interpret carefully.

Dear Editor,

I read with interest the published article by Chung et al.1 recently in your journal. Hepatitis A virus (HAV) infection continues to be a major health problem worldwide. Prevalence of HAV infection differs greatly in various parts of the world according to the geographic area, sanitary conditions and socioeconomic levels.2 As the authors presented the prevalence rate for anti-HAV Ab increased significantly, studies in various communities have shown that HAV prevalence rises with age.3 It will emphasize the need anti HAV vaccine during childhood in Korea especially when the symptomatic HAV infections have remarkably reported in Korea been increased during recent years.4 But there are some points that can help the readers for better understanding the issue. The living place of study group was urban and it may under-estimate the real prevalence of anti-HAV Ab in general population in Korea. In changing the developing countries to developed countries, the improvement in health status in not uniform and there are heterogeneity in distribution in every country.5 These limitation prevent for final conclusion regarding all of country in Korea, however the result is very important for health policy makers for any decision in future.

The decreasing tendency of seropositivity of hepatitis A virus (HAV) in young healthy Korean adults was observed in our study1 and this epidemiological shift was shown in changing the developing countries to developed countries.2-4 The point that we suggest was the catch-up vaccination for young adults especially 20s who have only 6.2% of HAV seropositivity because they are vulnerable to severe symptomatic infection. Also, the prevalence of HAV antibody was lower in high income group and the H. pylori-negative group among young adults (<50 aged), the groups are also considerable to candidates to screening for protective antibodies against HAV and vaccination because the mortality rate of hepatitis A becomes higher at older age.5 However, the improvement in health status is not uniform in the same country and the seroprevalence can be heterogeneity in distribution. Although the living place of subjects was not exactly evaluated in this study, most our subjects were collected in urban and high income group was relatively a large portion as we have already mentioned as a limitation of our study. It may underestimate the real prevalence of seroprevalence of HAV in general young population in Korea. According to a recent study based on the latest nationwide survey in Korea,6 the persons in their 20s in 2009 were found to be the most vulnerable to the infection of HAV with the lowest antibody positive rates (10.4% to 13.3%) regarding all of country evaluated including rural area. Thus, catch-up vaccination for young adults with a low antibody positive rated is to be considered in Korea. However, health policy in every country should be individualized.