Prevalence and Heterogeneity of Swine Influenza Virus in China From 2010 to 2025: A Systematic Review and Meta-Analysis.

Abstract

BACKGROUND: Swine influenza virus (SIV) is endemic in China, threatening the swine industry and public health. This meta-analysis estimated the national pooled prevalence of SIV (2010-2025) and identified key sources of heterogeneity. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, six databases were searched, yielding 73 eligible studies with 411,930 samples. A random-effects model pooled prevalence estimates, and subgroup analyses explored heterogeneity. RESULTS: The pooled SIV prevalence was 30.3% (95% confidence interval [CI]: 24.5%-36.4%) with extreme heterogeneity (&#x2009;=&#x2009;100%,&#x2009; < 0.001). Key drivers included diagnostic method (serological: 37.1% vs. virological: 2.6%), geography (Southwest China: 54.3%), and viral genotype (H1&#x2009;>&#x2009;H3). Sensitivity analysis confirmed robustness, but publication bias (Egger's test,= 0.0009) suggests potential overestimation. CONCLUSION: SIV is widespread in China but exhibits marked spatiotemporal and methodological variability. A single national prevalence figure is insufficient for risk assessment. Surveillance and control strategies must be targeted and context-specific. This study provides a critical, albeit potentially overestimated, epidemiological baseline for evidence-based interventions.