Comparative Analysis of Flight Volume Effects on COVID-19 and Influenza Transmission Across Variable Control Intensities, 2019–2024

BACKGROUND: Air travel has played a critical role in the global spread of infectious diseases, facilitating rapid movement of pathogens across continents. This study quantifies the effects of intercontinental flight volumes on both influenza and COVID-19 transmission patterns across countries with varying intensities of public health interventions. METHODS: We analyzed monthly global passenger numbers from January 2019 to July 2024, coupled with comprehensive surveillance data on both pathogens. Using a hierarchical Bayesian linear mixture modeling framework, we examined the relationship between flight volumes and disease activity while accounting for heterogeneity in public health and social measures. RESULTS: Our analysis reveals that increased flight volumes were significantly associated with both influenza activity and COVID-19 case and mortality rates, with Asian flight spreading rate demonstrating the strongest association with influenza transmission and COVID-19 case rates. These effects were consistently stronger for COVID-19 than influenza and more pronounced in countries with less stringent control measures. CONCLUSIONS: The comparative approach provides unique insights into how different respiratory pathogens respond to aviation-mediated exposures, demonstrating that targeted travel restrictions can effectively impede disease transmission when implemented alongside appropriate public health interventions. These findings have important implications for the development of pathogen-specific strategies for mitigating the international spread of emerging respiratory threats.