On March 17, 2020, this report was posted on-line as an MMWR Early Launch.
An outbreak of coronavirus illness 2019 (COVID-19) amongst passengers and crew on a cruise ship led to quarantine of roughly 3,700 passengers and crew that started on February 3, 2020, and lasted for almost 4 weeks on the Port of Yokohama, Japan (1). By February 9, 20 instances had occurred among the many ship’s crew members. By the top of quarantine, roughly 700 instances of COVID-19 had been laboratory-confirmed amongst passengers and crew. This report describes findings from the preliminary part of the cruise ship investigation into COVID-19 instances amongst crew members throughout February 4–12, 2020.
On February 1, a laboratory-confirmed case of COVID-19 was recognized in a passenger who had developed signs on January 23 and disembarked on January 25, earlier than the ship arrived in Yokohama. One other passenger with a laboratory-confirmed case of COVID-19 had developed signs on January 22 and was on the ship when it arrived in Yokohama on February 3. All symptomatic passengers have been examined upon arrival in Yokohama, and people with optimistic outcomes have been disembarked February 4 and 5. The index affected person for this outbreak couldn’t be decided. On February 5, passengers remaining on the ship have been requested to watch 14-day quarantine of their cabins. Roughly two thirds of the individuals on board have been passengers staying in cabins positioned on decks 5–12. The rest (N = 1,068) have been crew members, >80% of whose cabins have been on decks 2–4. Crew members remained on board the ship always and had not disembarked throughout port calls. After quarantine started, crew members continued to carry out their common duties, delivered meals to passengers, and remained of their cabins once they weren’t working; symptomatic crew members have been required to stay of their cabins.
As a result of the primary detected instances occurred amongst passengers who grew to become symptomatic on January 22 and 23, COVID-19 was seemingly transmitted first from passengers to crew members and subsequently unfold among the many crew, particularly amongst meals service employees. The primary case detected in a crew member occurred in a meals service employee who developed fever on February 2. An actual-time polymerase chain response take a look at carried out by the Yokohama quarantine workplace laboratory was optimistic for SARS-CoV-2, the etiologic agent of COVID-19, and the crew member was permitted to disembark in Yokohama on February 4. By February 9, a complete of 20 instances* amongst crew members had been laboratory-confirmed, together with three in those that reported shut contact with different crew members with laboratory-confirmed COVID-19 earlier than implementation of quarantine. Seven in poor health crew members had symptom onset inside 3 days of the beginning of quarantine, indicating that some SARS-CoV-2 transmission seemingly occurred earlier than the implementation of quarantine.
The crew eating space was recognized as the first space of congregation for the crew; passengers didn’t have entry to this a part of the ship. The earliest laboratory-confirmed COVID-19 instances in crew members occurred in meals service employees; 15 of the 20 confirmed instances in crew members occurred amongst meals service employees who ready meals for different crew members and passengers, and 16 of the 20 instances occurred amongst individuals with cabins on deck 3, the deck on which the meals service employees lived (Desk). Till February 6, no mechanism for systematic testing was carried out; solely crew members who visited the medical clinic with signs have been examined, and data on the entire variety of assessments administered just isn’t accessible.
The cruise ship firm administered a questionnaire to all crew members on February 3, at which period three crew members reported subjective fever. A second survey of crew members was performed on February 9, at which period fever was reported by 31 crew members, 20 (65%) of whom have been meals service employees.
Interviews have been performed with 9 crew members with confirmed COVID-19 on February 12, simply earlier than their disembarkation; three of those sufferers reported shut contact with different crew members with confirmed COVID-19 earlier than their signs started. These interviews indicated that an infection had apparently unfold amongst individuals whose cabins have been on the identical deck (deck 3) and who labored in the identical occupational group (meals service), most likely by contact or droplet unfold, which is in keeping with present understanding of COVID-19 transmission (2). Eight of 20 crew members with confirmed COVID-19 had cabin mates; investigators later realized that following disembarkation, as of March 4, 5 of the eight cabin mates had additionally developed COVID-19.
This investigation underscores the necessity for swift epidemiologic investigation as quickly as a COVID-19 case is detected in an space or group the place a lot of individuals collect in a closed or crowded setting (e.g., a cruise ship, music membership, well being care setting, sports activities enviornment, or gymnasium). These settings have been beforehand related to infections unfold by contact or droplet, reminiscent of influenza (3). Shut contacts of individuals with confirmed COVID-19 ought to self-quarantine and monitor their signs; individuals who develop COVID-19 signs whereas on board a ship needs to be remoted to restrict transmission to different passengers and crew.†
1Subject Epidemiology Coaching Program, Nationwide Institute of Infectious Ailments, Tokyo, Japan; 2Infectious Illness Surveillance Middle, Nationwide Institute of Infectious Ailments, Tokyo, Japan; 3Nationwide Institute of Infectious Ailments, Tokyo, Japan.
MMWR and Morbidity and Mortality Weekly Report are service marks of the U.S. Division of Well being and Human Providers.
Use of commerce names and industrial sources is for identification solely and doesn’t indicate endorsement by the U.S. Division of
Well being and Human Providers.
References to non-CDC websites on the Web are
offered as a service to MMWR readers and don’t represent or indicate
endorsement of those organizations or their packages by CDC or the U.S.
Division of Well being and Human Providers. CDC just isn’t accountable for the content material
of pages discovered at these websites. URL addresses listed in MMWR have been present as of
the date of publication.
All HTML variations of MMWR articles are generated from last proofs by an automatic course of.
This conversion may lead to character translation or format errors within the HTML model.
Customers are referred to the digital PDF model (https://www.cdc.gov/mmwr)
and/or the unique MMWR paper copy for printable variations of official textual content, figures, and tables.
Questions or messages relating to errors in formatting needs to be addressed to