Assessing the Pandemic Potential of Emerging Avian Influenza A(H5N1) in the United States Using the Viral Trait Assessment for Pandemics (ViTAP) Model

In an increasingly interconnected world, the threat of a devastating influenza pandemic looms large. Highly pathogenic avian influenza A(H5N1), with its high case fatality rate and potential for adaptation in avian reservoirs, is a prime candidate for triggering such a pandemic. We applied the Viral Trait Assessment for Pandemics (ViTAP) model, a quantitative framework, to assess the pandemic potential of H5N1 strains currently circulating in the United States. Through a systematic literature review and structured expert elicitation involving virologists and epidemiologists, we refined and validated ViTAP scores across 11 key viral traits. The resulting assessment yielded a final ViTAP score of 3.28 out of 5, placing the U.S. H5N1 strains in the moderate-to-high risk category. This elevated risk is driven by the virus high human fatality rate, its segmented RNA genome enabling reassortment, and its propensity for mutation. Sensitivity analyses highlight the transmission mode of the virus as a critical factor, with even minor increases in human-to-human spread dramatically escalating the pandemic threat. Comparisons with historical pandemics underscore the potential for H5N1 to rival the devastating impact of the 1918 H1N1 pandemic. Our findings emphasize the urgent need for enhanced surveillance in avian and mammalian hosts, targeted vaccine development, and comprehensive pandemic preparedness efforts. By demonstrating the utility of the ViTAP model for pandemic risk assessment, we provide a valuable tool to guide policy and interventions in the face of emerging zoonotic threats.