Enhanced sentinel surveillance for hepatitis B infection in 200 counties in China, 2013-2016.

Hepatitis B infection is a major public health challenge in China. Clinicians report hepatitis B cases to the National Notifiable Disease Reporting System. A 2007 study found that only 35% of hepatitis B cases that had been reported as acute infections met a rigorous case definition of acute hepatitis B, implying overreporting of new-onset infections. To increase the accuracy of reported acute hepatitis B infections, in 2013, we initiated enhanced hepatitis B surveillance in 200 sentinel counties. We compared incidences and proportions of different stages of hepatitis B infection before and after implementation of enhanced surveillance. We checked the accuracy of reported data and re-diagnosed hepatitis B cases reported as acute infection according to the enhanced diagnostic criteria and calculated positive predictive value(PPV) of acute hepatitis B reports. Compared to previous surveillance, with enhanced surveillance, the incidence of reported acute hepatitis B infection decreased by 53.7% and the proportion of unclassified hepatitis B infection was reduced by 79.4%. From 2013 to 2016, the PPV of acute hepatitis B increased (55.8% to 71.0%); PPV rates in western and rural areas were lower than in other areas. We recommend enhancing hepatitis B surveillance nationwide using these new standards, and raising western and rural areas clinicians' diagnostic and reporting capacity, and ensuring sufficient resources for IgM anti-HBc testing.