Changing Epidemiological Characteristics of Hepatitis A in Zhejiang Province, China: Increased Susceptibility in Adults

<div><p>Background</p><p>Hepatitis A is a common acute hepatitis caused by hepatitis A virus (HAV). Annually, it affects 1.4 million people worldwide. Between 1991 and 1994, HAV infections were highly endemic in Zhejiang Province (China), with 78,720 reported HAV infections per year. Hepatitis A vaccine came on the market in 1995 and was implemented for voluntary immunization. Since 2008, hepatitis A vaccine has been integrated into the national childhood routine immunization program.</p><p>Objective</p><p>To understand the current epidemiological profile of hepatitis A in Zhejiang Province since hepatitis A vaccine has been available for nearly two decades.</p><p>Methods</p><p>This study used the 2005–2014 National Notifiable Diseases Reporting System data to evaluate the incidence rate of notified hepatitis A cases in Zhejiang Province.</p><p>Results</p><p>The overall trend of incidence rate of notified hepatitis A cases significantly decreased from 2005 to 2014 (P< 0.001). During the study period, the reported incidence rate in individuals aged ≤19 years declined to the historically lowest record in 2014. Compared with individuals aged ≤19 years, those aged ≥20 years showed the highest incidence rate (P< 0.001). Majority of HAV infected cases were Laborers, accounting for approximately 70% of reported cases.</p><p>Conclusions</p><p>Childhood immunization strategy with hepatitis A vaccine seemed to be effective in decreasing notified hepatitis A incidence rate in individuals aged ≤19 years. Those aged ≥20 years were observed to be the most susceptible population. The vast majority of hepatitis A cases were notified among Laborers. Therefore, we strongly suggest that future preventive and control measures should focus more on adults, particularly Laborers, in addition to the current childhood hepatitis A vaccination programme.</p></div

Dose of Hepatitis A vaccines used and new-born population by year.

<p>Dose of Hepatitis A vaccines used and new-born population by year.</p

Hepatitis A incidence rate by gender and year.

<p>Hepatitis A incidence rate by gender and year.</p

Percentages of hepatitis A cases by occupation.

<p>Percentages of hepatitis A cases by occupation.</p

The incidence rates of counties in Zhejiang Province, 2008–2012.

<p>The incidence rates of counties in Zhejiang Province, 2008–2012.</p

The results of space-time cluster analysis for mild cases of Zhejiang Province, 2008–2012.

<p>The results of space-time cluster analysis for mild cases of Zhejiang Province, 2008–2012.</p

Age-specific EV71 seroprevalence summary in healthy children.

<p>Age-specific EV71 seroprevalence summary in healthy children.</p

The map of Zhejiang Province.

<p>The map of Zhejiang Province.</p

The partial correlations between the monthly proportions of EV71/Cox A16 and the case-severity rate.

<p>The partial correlations between the monthly proportions of EV71/Cox A16 and the case-severity rate.</p

The monthly distribution of the number of mild cases (A) and severe cases (B) during 2008–2012.

<p>The monthly distribution of the number of mild cases (A) and severe cases (B) during 2008–2012.</p