COVID-19: Preparation for Quarantine on the Diamond Princess Cruise Ship

Preparation for Quarantine on the Cruise Ship Diamond Princess. Spencer EA, Jefferson T, Heneghan C.

Published on July 2, 2020

Reference Yamahata Y, Shibata A. Preparation for Quarantine on the Cruise Ship Diamond Princess in Japan due to COVID-19. JMIR Public Health Surveill. 2020;6(2):e18821. Published 2020 May 11. 2020
Study type
Country Japan
Setting Cruise ship The Diamond Princess
Funding Details The authors did not receive any funding for this study.
Transmission mode Person to Person, Close contact, fomite
Exposures Cruise ship

Bottom Line

Infection rate was high and clinical harm was considerable onboard the cruise ship. A number of operational difficulties hampered ideal isolation and quarantine procedures onboard.

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.

What did they do?

Japan implemented a large-scale quarantine on the Diamond Princess cruise ship in an attempt to control the spread of the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in February 2020.

A passenger who disembarked from the ship in Hong Kong on January 25 developed a fever on January 30. This passenger was confirmed to be positive for COVID-19 on February 1. The ship arrived at Yokohama earlier than scheduled on February 3, at which time the quarantine began.

The authors worked as medical staff at the entrance of the Diamond Princess from February 14 to 17, 2020, when the number of RT-PCR–confirmed COVID-19 cases reached its peak. They facilitated the transport of people with positive RT-PCR results by coordinating with the hospital and transportation provider, depending on their condition. In addition to scheduling transportation, the authors arranged for emergency transportation of people whose symptoms worsened.

This study describes the medical activities initiated and the difficulties in implementing quarantine on a cruise ship. 

Reverse transcription–polymerase chain reaction (RT-PCR) tests for SARS-CoV-2 were performed for all 3,711 people (2,666 passengers and 1,045 crew) on board, in the following order:

  1. Symptomatic patients and their close contacts
  2. Elderly people aged 80 years or above and people with comorbidities
  3. People aged 75 years and above
  4. People aged 70 years and above
  5. All other passengers
  6. All crew members

Since a certain number of false-negative RT-PCR test results were expected, the negative results were labelled as “undetermined test results” until the last day of the 14-day quarantine period and negative results were reported at the time of the disembarkation.

Study reliability

This is all information deriving from one setting and pertinent to improving procedures for future outbreaks in similar settings. Further deaths have accrued after the follow-up period in the present study.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes Yes Yes No Unclear

What else should I consider?

This provides a detailed description of quarantine procedures on board the Diamond Princess.

The authors recommend for future infectious disease outbreaks, that better planning for how to deal with potential onboard cruise ships, including better plans for transferring cases to hospitals, and keeping crew as safe as passengers.

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.

Tom Jefferson

Tom Jefferson, epidemiologist.