Abstract
BackgroundHepatitis A vaccines have been highly effective in preventing hepatitis A. To investigate the epidemiology of hepatitis A in China after hepatitis A vaccine became available, we reviewed reported cases of hepatitis A and the use of hepatitis A vaccine in China during the period from 1990 through 2007.MethodsData from the National Notifiable Disease Reporting System from 1990 to 2007 and the Emergency Events Reporting System from 2004 to 2007 were reviewed and epidemiologic characteristics analyzed. Hepatitis A vaccine distribution between 1992 and 2007 was also reviewed.ResultsThe incidence of hepatitis A has declined by 90% since 1990, from 56 to 5.9 per 105/year. Declines in age-specific incidence were seen in all age groups, most dramatically among children younger than 10 years. Disease incidence still varies substantially: poorer western provinces have had the highest incidences since 2000. In high-incidence provinces, children younger than 10 years continue to have a high disease incidence. Only 50% of cases were laboratory-confirmed, and only 3% occurred in reported local outbreaks. Over 156 million doses of hepatitis A vaccine have been distributed since 1992, and use has continued to increase since 2003.ConclusionsIncidence of hepatitis A has decreased in all age groups, likely due to changing socioeconomic conditions and increasing hepatitis A vaccine use. Nevertheless, western populations remain at high risk, with transmission predominantly occurring among children. The epidemiology of hepatitis A transmission is not well understood. Improved surveillance with better laboratory confirmation is needed to monitor the impact of universal hepatitis A vaccination of young children; this strategy began to be implemented in 2008.
Highlights
Hepatitis A is an acute, usually self-limited infection of the liver caused by the hepatitis A virus (HAV)
We reviewed incidence data on reported hepatitis A from 1990 to 2007 from the National Notifiable Disease Reporting System (NNDRS), in which a reportable case is defined as an acute illness with discrete onset of symptoms with jaundice and/or elevated serum aminotransferase levels
In a recent 4-year period (2004–2007), between 68 667 and 93 587 cases of hepatitis A have been reported through the NNDRS; incidence in these years was 7.2/100 000, 5.6/100 000, 5.4/100 000, and 5.9/ 100 000, respectively
Summary
Hepatitis A is an acute, usually self-limited infection of the liver caused by the hepatitis A virus (HAV). Among children younger than 5 years, 70% of those infected are asymptomatic; in high prevalence areas, symptomatic cases are uncommon.[1] hepatitis A can result in a high disease burden, and is still considered a public health problem in many countries. During the 1980s and 1990s, improved sanitation resulted in an increase in the average age of hepatitis A onset in many countries, but most cases still occur in populations living in poor sanitary conditions.[2,3,4,5]. Children younger than 10 years continue to have a high disease incidence. Conclusions: Incidence of hepatitis A has decreased in all age groups, likely due to changing socioeconomic conditions and increasing hepatitis A vaccine use. Improved surveillance with better laboratory confirmation is needed to monitor the impact of universal hepatitis A vaccination of young children; this strategy began to be implemented in 2008
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