Evolution of swine influenza surveillance and one health governance in Taiwan: from zoonotic risk management to integrated preparedness.

Influenza A viruses (IAVs) remain a persistent global threat because of rapid antigenic change, frequent genetic reassortment, and cross-species transmission. Swine act as key "mixing vessels," permitting co-infection with avian and human strains and accelerating viral diversification and zoonotic risk. Effective veterinary surveillance is therefore critical for detecting viral evolution within swine populations and for providing early warning at the animal-human interface. Taiwan, home to approximately 5.5 million pigs and 23.4 million people, offers a representative case for examining how swine influenza surveillance has evolved in response to these challenges. This review describes the development of veterinary surveillance strategies from fragmented, event-driven monitoring to a coordinated One Health governance framework incorporating routine whole-genome sequencing, targeted serological surveillance, and coordinated data exchange across sectors. Key historical milestones include mass vaccination and culling programs, the 2009 pandemic response and recent zoonotic detections of H1N2v in humans (2021-2023), collectively evidencing ongoing bidirectional viral exchange. Episodes of severe human seasonal influenza activity, including H3N2-associated outbreaks, further highlighted the importance of coordinated surveillance across human and animal health sectors. By focusing on surveillance practices applied to animals, this review highlights the practical value of integrating molecular epidemiology, veterinary field monitoring, artificial intelligence (AI)-enabled technologies and cross-sector communication under a One Health framework. The Taiwanese experience demonstrates how strengthened veterinary surveillance can improve the sensitivity for detecting reassortment events, enhance traceability of viral spread, and support timely risk assessment in intensive livestock systems. These lessons offer a practical, replicable pathway for other countries aiming to overcome swine influenza surveillance fragmentation and strengthen pandemic preparedness under a One Health framework.