Will Hepatitis A Become a Vaccine-Preventable Disease?

Fifty years ago, hepatitis A was a common disease worldwide and most people had been infected with the hepatitis A virus (HAV) by the time they were young adults. Now, patterns of HAV transmission differ markedly among geographic regions throughout the world. In developing countries, most of the population is infected before 10 years of age, and HAV is the most frequent cause of acute hepatitis in children [1]. Most children less than 5 years of age do not have clinically evident infection, but they efficiently transmit HAV to their contacts in the household and in the community [2]. In more developed countries, the risk for infection is lower and most infections occur in older children and adults [1]. In many countries, changes in sanitation and socioeconomic level appear to have reduced the likelihood of infection with this enterically transmitted virus [1, 3]. Person-to-person contact is the primary mode of transmission, and food and water are infrequently implicated, although a massive outbreak of hepatitis A occurred in China when a susceptible young adult population consumed raw shellfish harvested from virus-contaminated waters [4-6].

In the United States, nationwide epidemics of hepatitis A occurred every 7 to 10 years until the mid-1970s, and approximately 60% of persons born before 1950 have been infected with HAV [6-8]. The endemicity of infection is considered low in this country; approximately 10% of persons less than 20 years of age have serologic evidence of infection [8]. However, low risk for infection is …