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. 2020 Feb 29:5:264-270.
doi: 10.1016/j.idm.2020.02.003. eCollection 2020.

Transmission potential of the novel coronavirus (COVID-19) onboard the diamond Princess Cruises Ship, 2020

Kenji Mizumoto  1   2   3 , Gerardo Chowell  3   4
Affiliations

Transmission potential of the novel coronavirus (COVID-19) onboard the diamond Princess Cruises Ship, 2020

Kenji Mizumoto et al. Infect Dis Model. .

Abstract

An outbreak of COVID-19 developed aboard the Princess Cruises Ship during January-February 2020. Using mathematical modeling and time-series incidence data describing the trajectory of the outbreak among passengers and crew members, we characterize how the transmission potential varied over the course of the outbreak. Our estimate of the mean reproduction number in the confined setting reached values as high as ~11, which is higher than mean estimates reported from community-level transmission dynamics in China and Singapore (approximate range: 1.1-7). Our findings suggest that R t decreased substantially compared to values during the early phase after the Japanese government implemented an enhanced quarantine control. Most recent estimates of R t reached values largely below the epidemic threshold, indicating that a secondary outbreak of the novel coronavirus was unlikely to occur aboard the Diamond Princess Ship.

Keywords: Confined settings; Corona; Cruise; Epidemic; Next generation matrix.

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Conflict of interest statement

None.

Figures

Fig. 1
Fig. 1
Observed and estimated number of the New Coronavirus (COVID-19) cases by type, onboard the Princess Cruises Ship, 2020 (n = 197). (A)–(C) Comparison of observed and predicted daily numbers of new cases by type. Black dots shows observed data, and light and dark indicates 95% and 50% credible intervals for posterior estimates, respectively. Day 1 on horizontal axis corresponds to January 20, 2020.
Fig. 2
Fig. 2
Time-dependent effective reproduction number of COVID-19 onboard the Princess Cruises Ship, 2020. The overall effective reproduction number were calculated from the dominant eigenvalue of next-generation matrix. Light and dark indicates 95% and 50% credible intervals for posterior estimates, respectively. Day 1 on horizontal axis corresponds to January 20, 2020. Horizontal grey dashed line shows the reproduction number at 1.0 for reference, below which incidence declines. Vertical dashed line indicates the day when quarantine was implemented (February 5, 2020).
Fig. 3
Fig. 3
Distribution of median effective reproduction number for overall and by transmission type, onboard the Princess Cruises Ship, 2020. P: Passenger, C: Crew.
See this image and copyright information in PMC

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