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

## TL;DR

This study finds that swine influenza virus is widespread in China, with significant variation in prevalence due to factors like testing methods and geography.

## Contribution

The study provides the first comprehensive meta-analysis of SIV prevalence in China from 2010 to 2025, identifying key sources of heterogeneity.

## Key findings

- The pooled SIV prevalence in China was 30.3% with high heterogeneity (I² = 100%).
- Diagnostic method, geography, and viral genotype significantly influenced prevalence estimates.
- Publication bias suggests the true prevalence may be lower than reported.

## Abstract

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.

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.

The pooled SIV prevalence was 30.3% (95% confidence interval [CI]: 24.5%–36.4%) with extreme heterogeneity (I
2 = 100%, p  < 0.001). Key drivers included diagnostic method (serological: 37.1% vs. virological: 2.6%), geography (Southwest China: 54.3%), and viral genotype (H1 > H3). Sensitivity analysis confirmed robustness, but publication bias (Egger’s test, p = 0.0009) suggests potential overestimation.

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.