Transmission routes of Covid-19 virus in the Diamond Princess Cruise ship

Pengcheng Xu; Hua Qian; Te Miao; Hui-ling Yen; Hongwei Tan; Benjamin J. Cowling; Yuguo J Li

The infection settings prior to the quarantine on Feb 5 might be similar to those norovirus outbreak reported in the cruise ships. Diamond Princess actually had an outbreak of gastroenteritis caused by norovirus in Feb 2016, in which 158 passengers and crew were sick on board (ABC News, 2016) . It is known that the norovirus infections on cruise ships affected the largest number of people (Harris et al., 2010) , often at hundreds. Crowdedness has been cited as an explanation for this cruise ship norovirus infection phenomenon (Harris et al., 2010, and Bert et al., 2014) . Surfaces on cruise ship public restrooms are known to have high potential for fecal contamination (Carling et al., 2009) . The same effect of crowdedness and fomite for the norovirus might have also happened to SARS-CoV-2 in this ship. The crowdedness and close contacts due to on-board leisure and social activities outside the staterooms could explain the observed higher infection among non-close contact passengers prior to the quarantine. According to the National Institute of Infectious Diseases (NIID), Japan website (NIDD, 2020), for the 536 Covid-19 cases among 2646 passengers, a higher cabin occupancy corresponds to a slightly higher attack rate, possibly due to the relatively smaller number of the within-cabin close contact transmission. Based on our retried data from a drawing, only 6 out of 75 passengers from 1-person cabins became confirmed cases (attack rate 8%), while for 2-person cabins, 485 of 2386 passengers were infected (20%), for 3-person cabins, 27 out of 125 (22%) and for 4-person cabins, 18 out of 60 (30%). All rights reserved. No reuse allowed without permission. the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.