CONTEXT: Federal public health travel restrictions (FPHTR) in the United States are implemented for persons who meet specific criteria to prevent spread of communicable diseases of public health concern. FPHTR can mitigate the risk of disease transmission during air travel and mitigating disease translocation between geographic areas. OBJECTIVE: To characterize and determine the extent of FPHTR implementation during the COVID-19 pandemic. DESIGN: Secondary data analysis. SETTING AND PARTICIPANTS: This report reviewed the U.S. public health response for 3010 persons traveling within, into, and out of, the U.S. who were placed on federal public health travel restrictions during the COVID-19 outbreak from January 1, 2020 to April 6, 2022. MAIN OUTCOME MEASURE: Total number and characteristics of persons with SARS-CoV-2 infection or high-risk exposure added to FPHTR. RESULTS: During this period, FPHTR were implemented for 3010/5460 (55%) persons who were reported to CDC as having tested positive for SARS-CoV-2, or being identified as close contacts of a person with COVID-19, with intention to travel. Of those added to FPHTR lists, 2023/3010 (67%) had confirmed SARS-CoV-2 infection, 975/3010 (32%) were close contacts, and 12/3010 (0.4%) were reasonably believed to have COVID-19 but later confirmed to have another diagnosis and removed. Twenty-six percent (793/3010) of SARS-CoV-2-related FPHTR were for persons reported to CDC after testing positive for SARS-CoV-2 at a testing site located within a U.S. airport. CONCLUSIONS: The extensive application of FPHTR for more than 3000 persons over a period of 29 months during the COVID-19 pandemic was unprecedented. The additional use of FPHTR required extraordinary effort and collaboration among CDC staff and local/state public health agencies for case investigation, reporting, exchange of information, and communication with travelers for case management. Use of this tool should be considered within the context current transmission risk and disease severity.

The global spread of the influenza A(H1N1)pdm09 virus (pH1N1) associated with travelers from North America during the onset of the 2009 pandemic demonstrates the central role of international air travel in virus migration. To characterize risk factors for pH1N1 transmission during air travel, we investigated travelers and airline employees from four North American flights carrying ill travelers with confirmed pH1N1 infection. Of 392 passengers and crew identified, information was available for 290 (74%) passengers were interviewed. Overall attack rates for acute respiratory infection and influenza-like illness 1-7 days after travel were 5.2% and 2.4% respectively. Of 43 individuals that provided sera, 4 (9.3%) tested positive for pH1N1 antibodies, including 3 with serologic evidence of asymptomatic infection. Investigation of novel influenza aboard aircraft may be instructive. However, beyond the initial outbreak phase, it may compete with community-based mitigation activities, and interpretation of findings will be difficult in the context of established community transmission.