Effect of containment strategies for respiratory diseases on infections imported via international travel to the USA: a modelling study.

Abstract

To examine outcomes from respiratory pathogens containment strategies focused on international travellers. We developed a compartmental model generalisable to respiratory infectious diseases, in which international travellers interact with each other and airline/airport workers during transit. We used SARS-CoV-2 Omicron surge data (basic reproduction number (R₀): 9.5) as a case example and performed sensitivity and scenario analyses, including varying the R₀ for different respiratory pathogens. A US high-volume airport. Simulated international travellers and airline/airport workers. Projection of new and imported SARS-CoV-2 infections without intervention (<i>No Intervention</i>); pre-travel screening for travellers who intend to travel (intended travellers) with PCR (<i>Pre-travel PCR</i>); or antigen testing (<i>Pre-travel Ag</i>); mask-wearing guidance for travellers and workers (<i>Mask-wearing</i>); and a <i>Combined</i> strategy (<i>Pre-travel PCR & Mask-wearing</i>). The number of new and imported respiratory disease infections over the 90-day simulation period. Over the 90-day simulation, the number of infected travellers entering the USA would be: 1 155 580 (27.2% of 4.2 million (M) intended travellers) with <i>No Intervention</i>; 709 560/4.2M (16.7%) with <i>Pre-travel PCR</i>; 862 330/4.2M (20.3%) with <i>Pre-travel Ag</i>; 1033 820/4.2M (24.4%) with <i>Mask-wearing</i>; and 650 480/4.2M (15.3%) with <i>Combined</i>. The number of new infections among airline/airport workers would be: 25 670 (73.3% of 35 000 workers) with <i>No Intervention</i>; 25 260 (72.2%) in <i>Pre-travel PCR</i>; 25 590 (73.1%) in <i>Pre-travel Ag</i>; 24 630 (70.4%) in <i>Mask-wearing</i>; and 18 770 (53.6%) in <i>Combined</i>. In scenario analyses, the most impactful parameters were R₀ of the respiratory pathogen and population immunity level. A <i>Combined</i> strategy of pre-travel PCR testing and mask-wearing would most effectively reduce respiratory infection among international travellers and airline/airport workers, but would still allow a substantial number of infections to enter the USA, especially when the pathogen is highly transmissible.