Improving Influenza Nomenclature Based on Transmission Dynamics

Influenza A viruses (IAVs) evolve rapidly, exhibit zoonotic potential, and frequently adapt to new hosts, often establishing long-term reservoirs. Despite advancements in genetic sequencing and phylogenetic classification, current influenza nomenclature systems remain static, failing to capture evolving epidemiological patterns. This rigidity has led to misinterpretations in public health responses, economic disruptions, and confusion in scientific communication. Existing nomenclature does not adequately reflect real-time transmission dynamics or host adaptations, limiting its usefulness for public health management. The misnomer "swine flu" for the 2009 H1N1 pandemic (A(H1N1)pdm09) has created undue public confusion and potential stigma despite no direct pig-to-human transmission. This review proposes a real-time, transmission-informed nomenclature system that prioritizes host adaptation and sustained transmissibility (R0) to align influenza classification with epidemiological realities and risk management. Through case studies of H1N1pdm09, H5N1, and H7N9, alongside a historical overview of influenza naming, we demonstrate the advantages of integrating transmission dynamics into naming conventions. Additionally, we discuss how a transmission-based framework can enhance public health responses and propose research and surveillance strategies to support its implementation. Adopting a real-time, transmission-informed approach will improve pandemic preparedness, strengthen global surveillance, and enhance influenza classification for scientists, policymakers, and public health agencies.