Epidemiological features and direct medical costs of norovirus acute gastroenteritis in China

Norovirus is a leading global cause of acute gastroenteritis (AGE), yet comprehensive data on its disease and economic burden across all age groups requiring medical consultation in China remains scarce, hindering evidence-based public health strategy formulation. A multi-center retrospective study was conducted on 23,527 AGE patients who underwent norovirus testing at medical institutions in four Chinese provinces between 2018 and 2024. The logistic regression models were used to analyze the related factors with norovirus infection rates, hospitalization risks, complication incidence, and direct medical costs. National annual direct medical burden of norovirus infection was estimated by combining study data with national population census and epidemiological survey data. The overall norovirus positive rate was 18.80% (95% CI 18.30%-19.30%), with a significantly higher rate in inpatients (26.15%, 95% CI 25.28%-27.04%) than outpatients (13.78%, 95% CI 13.21%-14.36%). Children < 5 years old had the highest positive rate (30.49%, 95% CI 29.56%-31.43%. A total of 18.97% (95% CI 17.84%–20.16%) of norovirus-positive patients developed at least one potential complication concurrent with norovirus-positive acute gastroenteritis, among which dehydration (11.28%, 95% CI 10.39%–12.25%) was the most prevalent, followed by convulsions (5.52%, 95% CI 4.88%–6.23%). The median direct medical costs for inpatients (CNY 4,580, IQR 3,129–6,402) was far higher than outpatients (CNY 230 IQR 128–354), with the elderly ≥ 65 years having the highest per capita direct medical costs (CNY 5,322, IQR 2,411–10,798). The national annual direct medical cost of norovirus infection was estimated at CNY 20.23 billion, with children < 5 years bearing a medical burden 11.2 times that of the elderly ≥ 60 years. Norovirus infection among hospital-tested patients in China exhibits the disparities in disease burden by age, region and season. Children aged < 5 years tended to experience more severe clinical manifestations, whereas patients aged ≥ 65 years appeared to bear higher individual medical expenditure in our hospital-based samples. Age-targeted public health strategies and regionally tailored healthcare resource allocation are urgently needed to address the heterogeneous disease burden of norovirus infection in China.