Public Health Responses to COVID-19 Outbreaks on Cruise Ships — Worldwide, February–March 2020

Leah F. Moriarty, MPH; Mateusz M. Plucinski, PhD; Barbara J. Marston, MD; Ekaterina V. Kurbatova, MD, PhD; Barbara Knust, DVM; Erin L. Murray, PhD; Nicki Pesik, MD; Dale Rose, PhD; David Fitter, MD; Miwako Kobayashi, MD, PhD; Mitsuru Toda, PhD; Paul T. Canty, MD; Tara Scheuer, MPH; Eric S. Halsey, MD; Nicole J. Cohen, MD; Lauren Stockman, MPH; Debra A. Wadford, PhD; Alexandra M. Medley, DVM; Gary Green, MD; Joanna J. Regan, MD; Kara Tardivel, MD; Stefanie White, MPH; Clive Brown, MD; Christina Morales, PhD; Cynthia Yen, MPH; Beth Wittry, MPH; Amy Freeland, PhD; Sara Naramore, MPH; Ryan T. Novak, PhD; David Daigle, MPH; Michelle Weinberg, MD; Anna Acosta, MD; Carolyn Herzig, PhD; Bryan K Kapella, MD; Kathleen R. Jacobson, MD; Katherine Lamba, MPH; Atsuyoshi Ishizumi, MPH, MSc; John Sarisky, MPH; Erik Svendsen, PhD; Tricia Blocher, MS; Christine Wu, MD; Julia Charles, JD; Riley Wagner, MPH; Andrea Stewart, PhD; Paul S. Mead, MD; Elizabeth Kurylo, MCM; Stefanie Campbell, DVM; Rachel Murray, MPH; Paul Weidle, PharmD; Martin Cetron, MD; Cindy R. Friedman, MD


Morbidity and Mortality Weekly Report. 2020;69(12):347-352. 

In This Article

Diamond Princess

On January 20, 2020, the Diamond Princess cruise ship departed Yokohama, Japan, carrying approximately 3,700 passengers and crew (Table). On January 25, a symptomatic passenger departed the ship in Hong Kong, where he was evaluated; testing confirmed SARS-CoV-2 infection. On February 3, the ship returned to Japan, after making six stops in three countries. Japanese authorities were notified of the COVID-19 diagnosis in the passenger who disembarked in Hong Kong, and the ship was quarantined. Information about social distancing and monitoring of symptoms was communicated to passengers. On February 5, passengers were quarantined in their cabins; crew continued to work and, therefore, could not be isolated in their cabins.[6] Initially, travelers with fever or respiratory symptoms and their close contacts were tested for SARS-CoV-2 by reverse transcription–polymerase chain reaction (RT-PCR). All those with positive test results were disembarked and hospitalized. Testing was later expanded to support a phased disembarkation of passengers, prioritizing testing of older persons, those with underlying medical conditions, and those in internal cabins with no access to the outdoors. During February 16–23, nearly 1,000 persons were repatriated by air to their home countries, including 329 persons who returned to the United States and entered quarantine or isolation.§,¶

The remaining passengers who had negative SARS-CoV-2 RT-PCR test results,** no respiratory symptoms, and no close contact with a person with a confirmed case of COVID-19 completed a 14-day ship-based quarantine before disembarkation. Those passengers who had close contact with a person with a confirmed case completed land-based quarantine, with duration determined by date of last contact. After disembarkation of all passengers, crew members either completed a 14-day ship-based quarantine, were repatriated to and managed in their home country, or completed a 14-day land-based quarantine in Japan.

Overall, 111 (25.9%) of 428 U.S. citizens and legal residents did not join repatriation flights either because they had been hospitalized in Japan or for other reasons. To mitigate SARS-CoV-2 importation into the United States, CDC used temporary "Do Not Board" restrictions[7] to prevent commercial airline travel to the United States,†† and the U.S. Departments of State and Homeland Security restricted travel to the United States for non-U.S. travelers.

Among 3,711 Diamond Princess passengers and crew, 712 (19.2%) had positive test results for SARS-CoV-2 (Figure 1). Of these, 331 (46.5%) were asymptomatic at the time of testing. Among 381 symptomatic patients, 37 (9.7%) required intensive care, and nine (1.3%) died.[8] Infections also occurred among three Japanese responders, including one nurse, one quarantine officer, and one administrative officer.[9] As of March 13, among 428 U.S. passengers and crew, 107 (25.0%) had positive test results for COVID-19; 11 U.S. passengers remain hospitalized in Japan (median age = 75 years), including seven in serious condition (median age = 76 years).

Figure 1.

Cumulative number of confirmed coronavirus disease 2019 (COVID-19) cases* by date of detection — Diamond Princess cruise ship, Yokohama, Japan, February 3–March 16, 2020
Source: World Health Organization (WHO) coronavirus disease (COVID-2019) situation reports.
*Decline in cumulative number of cases on February 13 and February 25 due to correction by WHO for cases that had been counted twice.

§Quarantine was used for persons who were exposed; isolation was used for persons who had positive test results for SARS-CoV-2.
Movement for one person with resolved COVID-19 was not restricted.
**Based on Japanese testing procedures, which at the time included taking one oropharyngeal swab.
††Travel restrictions were lifted when persons had either completed a 14-day monitoring period without symptoms or had met clinical criteria for release from isolation.