Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020

Euro Surveill. 2020 Mar;25(10):2000180. doi: 10.2807/1560-7917.ES.2020.25.10.2000180.

Abstract

On 5 February 2020, in Yokohama, Japan, a cruise ship hosting 3,711 people underwent a 2-week quarantine after a former passenger was found with COVID-19 post-disembarking. As at 20 February, 634 persons on board tested positive for the causative virus. We conducted statistical modelling to derive the delay-adjusted asymptomatic proportion of infections, along with the infections' timeline. The estimated asymptomatic proportion was 17.9% (95% credible interval (CrI): 15.5-20.2%). Most infections occurred before the quarantine start.

Keywords: COVID-19; Japan; asymptomatic; corona; outbreak; quarantine.

MeSH terms

  • Adolescent
  • Adult
  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Asymptomatic Infections*
  • Betacoronavirus / genetics
  • Betacoronavirus / isolation & purification*
  • Child
  • Child, Preschool
  • Coronavirus Infections / diagnosis*
  • Coronavirus Infections / epidemiology
  • Coronavirus Infections / transmission
  • Disease Outbreaks*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Models, Statistical
  • Pneumonia, Viral / diagnosis*
  • Pneumonia, Viral / epidemiology
  • Pneumonia, Viral / transmission
  • Quarantine
  • Sex Distribution
  • Ships*
  • Travel*
  • Young Adult

Supplementary concepts

  • COVID-19
  • severe acute respiratory syndrome coronavirus 2