ger and 1,606-bed capacity) with 33 crew members sailed from Piraeus, Greece, to Cesme, Turkey, where an additional 350 crew members embarked on March 8, 2020 (1). For 21 days, the ship sailed without any disembarkations or embarkations until the fi rst suspected coronavirus disease (COVID-19) case was reported to the health authority of the Piraeus port on March 28, 2020. We describe results of the outbreak investigation, including risk factors for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
The StudyWe collected data by completing standardized forms through interviews and medical examination of all travelers onboard and by reviewing the ship records and logs. We used descriptive statistics to analyze the study variables and performed univariate and multivariate analyses.In conducting clinical management of cases, we followed guidelines from the Hellenic National Public Health Organization (NPHO) for health measures on travelers and repatriation, which were based on the European Union Healthy Gateways Joint Action advice for management of COVID-19 cases onboard ships (2) (Appendix Table 1, https:// wwwnc.cdc.gov/EID/article/27/7/21-0398-App1. pdf). NPHO and the Piraeus Port Health Authority provided passengers with information about using medical facemasks at all times when outside of their cabins, as well as handwashing, physical distancing, and cleaning and disinfecting cabins; ship offi cers supervised.Food preparation and laundry and cleaning services were halted; travelers were instructed to clean their own cabins and store used linens in plastic bags. Cleaning and disinfection of the terminal was done by a private company under supervision of the Piraeus Port Health Authority, after all travelers disembarked the ship at the port of Piraeus. A catering company provided packaged meals; personal hygiene supplies were also provided (including facemasks and hand sanitizer). Methods and results of the environmental sampling have been published elsewhere (3).We collected oropharyngeal specimens from all travelers onboard. Molecular tests for SARS-CoV-2 detection were performed by using the Cobas SARS-CoV-2 test qualitative assay and the Cobas 6800/8800 System (La Roche, https://www.roche. com). Serologic tests were performed on blood