Testing for SARS-CoV-2 among cruise ship travelers repatriated to the United States, February–March 2020

Background In early 2020, an outbreak of coronavirus disease 2019 occurred among passengers and crew of the Diamond Princess cruise ship. During February 16–17, some US citizens, residents, and their partners voluntarily repatriated to the US from Japan. Methods We conducted a retrospective, longitudinal evaluation of repatriated travelers where the outcome of interest was a positive test for SARS-CoV-2. Travelers who tested positive for SARS-CoV-2 were isolated in hospitals or at home under county isolation orders and underwent serial testing by real-time reverse transcription polymerase chain reaction (RT-PCR) approximately every other day, as contemporaneous US guidance required two consecutive negative tests collected ≥24 hours apart and symptom improvement before release from isolation. Results Among quarantined repatriated travelers, 14% tested positive for SARS-CoV-2. One-fifth of infected travelers initially tested negative but were identified on subsequent testing. All infected travelers remained asymptomatic or developed mild symptoms during isolation. Many travelers remained in prolonged isolation because of persistent viral detection based on contemporaneous policies. Conclusion Our findings support testing within 3-5 days after possible SARS-CoV-2 exposure to comprehensively identify infections and mitigate transmission and lend support to symptom- and time-based isolation recommendations, rather than test-based criteria. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The authors received no financial support for the research, authorship, and/or publication of this article. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Case investigation, data collection, and analysis were conducted for public health purposes. This project was reviewed by the National Center for Emerging and Zoonotic Infectious Diseases Human Subjects Contact at the Centers for Disease Control and Prevention (CDC). The project was determined to meet the requirements of public health surveillance covered by the U.S. Department of Health and Human Services Policy for the Protection of Human Research Subjects as defined in 45 CFR 46.102, and the decision was made that this project was nonresearch and did not require ethical review by the CDC Human Research Protection Office. Ethical approval was waived and informed consent was not required. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data referred to in the manuscript are provided. * COVID-19 : coronavirus disease 2019 SARS-CoV-2 : severe acute respiratory syndrome coronavirus 2 RT-PCR : real-time reverse transcription polymerase chain reaction