Epidemiology of Coronavirus Disease Outbreak among Crewmembers on Cruise Ship, Nagasaki City, Japan, April 2020

Abstract

In April 2020, a coronavirus disease (COVID-19) outbreak occurred on the cruise ship Costa Atlantica in Nagasaki, Japan. Our outbreak investigation included 623 multinational crewmembers onboard on April 20. Median age was 31 years; 84% were men. Each crewmember was isolated or quarantined in a single room inside the ship, and monitoring of health status was supported by a remote health monitoring system. Crewmembers with more severe illness were hospitalized. The investigation found that the outbreak started in late March and peaked in late April, resulting in 149 laboratory-confirmed and 107 probable cases of infection with severe acute respiratory syndrome coronavirus 2. Six case-patients were hospitalized for COVID-19 pneumonia, including 1 in severe condition and 2 who required oxygen administration, but no deaths occurred. Although the virus can spread rapidly on a cruise ship, we describe how prompt isolation and quarantine combined with a sensitive syndromic surveillance system can control a COVID-19 outbreak.

Keywords: COVID-19; Japan; SARS-CoV-2; coronavirus disease; cruise ship; epidemiology; outbreak; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.

Figure 1

Number of incident cases of persons with body temperature >37.1°C and number of prevalent cases of persons with body temperature >37.1°C or any sign or symptom of coronavirus disease on a cruise ship, Nagasaki, Japan, March 14–May 29, 2020. A) Number of persons with illness onset, by date. Crewmembers started disembarking on May 3. B) Daily number of crewmembers who reported having a body temperature >37.1°C or coronavirus disease signs or symptoms. Signs or symptoms other than fever: cough, nasal congestion, sore throat, headache, olfactory dysfunction, taste disorder, conjunctival congestion, diarrhea, myalgia or arthralgia, fatigue, shortness of breath, and nausea or vomiting.

Figure 2

Initial cabin room locations of the crewmembers on cruise ship where a coronavirus disease outbreak occurred, Nagasaki, Japan, 2020. A) Red indicates distribution of crewmembers with onset of body temperature >37.1°C during March 22–27. Green indicates cabin rooms of crewmembers who did not have a body temperature >37.1°C. B) Red indicates distribution of crewmembers with onset of body temperature >37.1°C during March 22–April 19. Green indicates cabin rooms of crewmembers who did not have a body temperature >37.1°C.