Use of US Public Health Travel Restrictions during COVID-19 Outbreak on Diamond Princess Ship, Japan, February-April 2020

Abstract

Public health travel restrictions (PHTR) are crucial measures during communicable disease outbreaks to prevent transmission during commercial airline travel and mitigate cross-border importation and spread. We evaluated PHTR implementation for US citizens on the Diamond Princess during its coronavirus disease (COVID-19) outbreak in Japan in February 2020 to explore how PHTR reduced importation of COVID-19 to the United States during the early phase of disease containment. Using PHTR required substantial collaboration among the US Centers for Disease Control and Prevention, other US government agencies, the cruise line, and public health authorities in Japan. Original US PHTR removal criteria were modified to reflect international testing protocols and enable removal of PHTR for persons who recovered from illness. The impact of PHTR on epidemic trajectory depends on the risk for transmission during travel and geographic spread of disease. Lessons learned from the Diamond Princess outbreak provide critical information for future PHTR use.

Keywords: COVID-19; Diamond Princess; Japan; SARS-CoV-2; United States; cluster; coronavirus disease; cruise ship; epidemic; pandemic; public health; respiratory infections; severe acute respiratory syndrome coronavirus 2; travel restrictions; viruses; zoonoses.

Figure 1

Implementation of PHTR for Diamond Princess cruise ship passengers and crew during the coronavirus disease outbreak, Japan, February 2020, including locations, monitoring plans, and criteria for PHTR removal for persons who tested positive for the virus (cases) and those who did not (non-cases). CDC, US Centers for Disease Control and Prevention; COVID-19, coronavirus disease; PHTR, public health travel restrictions; SARS-COV-2, severe acute respiratory syndrome coronavirus 2.

Figure 2

Significant disembarkation and monitoring events during a period of PHTR implemented for nonrepatriated US citizens and residents on the Diamond Princess cruise ship during the coronavirus disease pandemic, Japan, February 19–April 15, 2020. PHTR, public health travel restrictions.

Figure 3

Final disposition (hospitalized for COVID-19 vs. entered active monitoring) of US citizen passengers and crew of the Diamond Princess cruise ship who remained in Japan following US repatriation flights and were subject to public health travel restrictions during the COVID-19 outbreak, 2020. Repatriation flights occurred on February 17, 2020. The Diamond Princess cruise ship quarantine mandated by Japan ended on February 19,^,2020; by that date, 67 persons had disembarked, 3 of whom had not tested positive for SARS-CoV-2 at that time. CDC, US Centers for Disease Control and Prevention; COVID-19, coronavirus disease; SARS-COV-2, severe acute respiratory syndrome coronavirus 2.

Figure 4

Whisker plot for days between notification of a positive SARS-CoV-2 test result and removal of PHTR for passengers and crew on board the Diamond Princess cruise ship who remained in Japan after US repatriation flights, by type of criteria met for PHTR removal. Horizontal line within the box is the median; bottom line of box is first quartile (25%), top line of box is third quartile (75%). Whiskers represent the minimum (bottom) and maximum (top) number of days. Dots represent outliers. PHTR, public health travel restrictions; SARS-COV-2, severe acute respiratory syndrome coronavirus 2.