The great divergence of viral hepatitis in China, 2005–2020: vaccine-driven decline, diagnosis-driven rise, and the hepatitis E exception in a five-type surveillance panel

Abstract Background China's viral hepatitis landscape has been reshaped by vaccination, expanded diagnostics, and improved laboratory typing, yet the five serotypes have almost always been studied in isolation. Whether the rising reported incidence of hepatitis E—the only enteric type still increasing—reflects transmission, ascertainment, demography, or climate remains unresolved. We compared all five types on the same panel with the same methods. Methods We assembled a 31-province, 192-month (2005–2020), age-stratified panel of nationally reported cases and deaths (20 763 781 cases; 12 742 deaths). Joinpoint regression quantified trends; the Edwards test characterised seasonality; Kitagawa decomposition (dual endpoints 2005→2019 and 2005→2020) separated rate from age-structure effects; and identical two-stage distributed lag non-linear models with warming attribution were fitted for hepatitis A and E. Hepatitis E mechanistic estimates are cited from a companion study. Results Three trajectories emerged. Hepatitis A fell 10·3% per year (− 20·4% after the 2008 immunization-programme introduction; −96% at ages 5–14); hepatitis B was flat in aggregate (− 0·5% per year) while collapsing 13·9% per year at ages 0–19 and rising 4·1% per year at ages ≥ 60. Hepatitis C rose 10·0% per year before plateauing after 2012; unspecified hepatitis fell 11·9% per year, benchmarking improving ascertainment. Hepatitis E alone rose (+ 3·6% per year), overtaking hepatitis A from 2012; its rise preceded the steepest typing gains and was four-fifths a rate effect. The two enteric types diverged on geography (west versus east), season (summer versus early spring), age (childhood versus old age), and temperature response (negative versus positive). Warming attribution was − 969 cases for hepatitis A versus + 2 300 for hepatitis E. Hepatitis E case fatality (1·09 per 1 000) was threefold that of hepatitis A, with 57% of deaths at ages ≥ 60. Conclusions Hepatitis E is neither an ascertainment artefact nor a uniform climate response but the residual frontier of China's hepatitis transition: a foodborne infection of an ageing population, amplified by warmth and unreached by existing interventions. Priorities include routine hepatitis E testing in older adults with acute hepatitis, vaccine evaluation for high-risk and elderly groups, and inclusion of this burden in climate-adaptation planning.