Waning of anti-HAV immunity in Shijiazhuang prefecture, Hebei province, China: A comparison of seroprevalence between 1992 and 2011
2014
Chen, Ying | Zhang, Xin-Jiang | Zhao, Yu-Liang | Zhang, Yan-Hong | Wang, Song-Mei | Hao, Zhi-Yong | Zhang, Zhi-Yong | Ma, Jing-Chen | Fang, Yun | Wang, Xuan-Yi
To study the epidemiological patterns of hepatitis A, and immunity of entire population in Shijiazhuang prefecture, Hebei province, a former hyper-endemic area in north China.Cross-sectional, seroprevalence surveys with two-stage cluster sampling were conducted among population older than 2-year between 1992 and 2011. During the 2011 serological survey, blood samples from infants <18 months without hepatitis A immunization history were also collected to determine maternal anti-HAV antibody. Serum samples were tested for anti-HAV antibody by domestic reagent or Abbott reagent. Viral hepatitis incidence rates and gross domestic product data were derived from local governmental statistics.Concomitant with the reduction of reported hepatitis A cases between 1992 and 1996 was a significant decline of HAV infections. The average prevalence decreased from 93.6% to 41.9%, and the average age at new infection was postponed from infancy to adolescence. This was attributed to improved socio-economic conditions. With intensive vaccination, a return of new seroconversion rate and seroprevalence was observed. A well fitted exponential regression equation (R2=0.96, p<0.0001) modeled that the maternal antibody would wane to <20mIU/mL at 13 months.Benefiting from the booming economy, rapid improvement in sanitation, safe water supply, and implementation of hepatitis A vaccines, the epidemiological pattern of hepatitis A moved from high to intermediate endemicity in Shijiazhuang. Policy makers should be aware of the waning of immunity in entire population, and adapt immunization strategy timely, to ensure a lifelong protection against hepatitis A virus.
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