On August 29, 2021, the United States government oversaw the emergent establishment of Operation Allies Welcome (OAW), led by the U.S. Department of Homeland Security (DHS) and implemented by the U.S. Department of Defense (DoD) and U.S. Department of State (DoS), to safely resettle U.S. citizens and Afghan nationals from Afghanistan to the United States. Evacuees were temporarily housed at several overseas locations in Europe and Asia* before being transported via military and charter flights through two U.S. international airports, and onward to eight U.S. military bases,(†) with hotel A used for isolation and quarantine of persons with or exposed to certain infectious diseases.(§) On August 30, CDC issued an Epi-X notice encouraging public health officials to maintain vigilance for measles among Afghan evacuees because of an ongoing measles outbreak in Afghanistan (25,988 clinical cases reported nationwide during January-November 2021) (1) and low routine measles vaccination coverage (66% and 43% for the first and second doses, respectively, in 2020) (2).

The 2014-2016 Ebola epidemic in West Africa influenced how public health officials considered migration and emerging infectious diseases. Responding to the public's concerns, the US government introduced enhanced entry screening and post-arrival monitoring by public health authorities to reduce the risk of importation and domestic transmission of Ebola while continuing to allow travel from West Africa. This case study describes a new initiative, the Check and Report Ebola (CARE+) program that engaged travelers arriving to the United States from countries with Ebola outbreaks. The Centers for Disease Control and Prevention employed CARE ambassadors, who quickly communicated with incoming travelers and gave them practical resources to boost their participation in monitoring for Ebola. The program aimed to increase travelers' knowledge of Ebola symptoms and how to seek medical care safely, increase travelers' awareness of monitoring requirements, reduce barriers to monitoring, and increase trust in the US public health system. This program could be adapted for use in future outbreaks that involve the potential importation of disease and require the education and active engagement of travelers to participate in post-arrival monitoring.

On March 11, 2011, a magnitude 9.0 earthquake and subsequent tsunami damaged nuclear reactors at the Fukushima Daiichi complex in Japan, resulting in radionuclide release. In response, US officials augmented existing radiological screening at its ports of entry (POEs) to detect and decontaminate travelers contaminated with radioactive materials. During March 12 to 16, radiation screening protocols detected 3 travelers from Japan with external radioactive material contamination at 2 air POEs. Beginning March 23, federal officials collaborated with state and local public health and radiation control authorities to enhance screening and decontamination protocols at POEs. Approximately 543 000 (99%) travelers arriving directly from Japan at 25 US airports were screened for radiation contamination from March 17 to April 30, and no traveler was detected with contamination sufficient to require a large-scale public health response. The response highlighted synergistic collaboration across government levels and leveraged screening methods already in place at POEs, leading to rapid protocol implementation. Policy development, planning, training, and exercising response protocols and the establishment of federal authority to compel decontamination of travelers are needed for future radiological responses. Comparison of resource-intensive screening costs with the public health yield should guide policy decisions, given the historically low frequency of contaminated travelers arriving during radiological disasters.