Evidence Summary

Of those tested, 696 (19%) tested positive for COVID-19, of which 410 (59%) were asymptomatic. 

As of March 8, 2020, 31 patients (4.5% of patients with positive RT-PCR results) were hospitalized and required ventilator support or intensive care, and seven patients had died. 54% of the asymptomatic patients with a positive RT-PCR result had lung opacities on chest computed tomography. 

There were many difficulties in implementing quarantine, such as creating a dividing traffic line between infectious and noninfectious passengers, finding hospitals and transportation providers willing to accept these patients, transporting individuals, language barriers, and supporting daily life. 

Clinical challenges

The speed at which the patients changed from being asymptomatic or mild to severe was very high. About 10% of asymptomatic people developed symptoms during a 6-hour transport, and 10% to 20% of them worsened rapidly to a state in which intubation was considered within 24 hours. It was not possible to maintain as high a safety level for the crew as for the passengers.

Operational challenges:

The structure of the cruise ship made it difficult to carry out the medical services required for an outbreak of an emerging infectious disease.  At quarantine inception, information on the virus was very limited and practice had to be precautionary and developed as information emerged.

In particular, the authors noted that 

• One of the elevator halls may have been a transmission point because it was impossible for infected and non-infected people to use the elevator separately.
• Finding appropriate and available isolation facilities onshore was challenging
• Disembarkation procedures required passengers to walk and carry their own baggage, which was slow and difficult for many, particularly the elderly. 
• Often neither Japanese nor English was spoken, making it very difficult to explain procedures. Sometimes, the medical staff had to ask the crew to interpret the command, even if it increased the risk of infection. 
• Since all passengers were isolated in each cabin, supplies had to be delivered daily to each room. There were people of various nationalities and religions aboard, and it was necessary to consider religious taboos and allergies. The crew members had to keep working under the risk of infection.
• The disposal of the sewage was a challenge and eventually, a service came to extract sewage from the ship.