COVID-19 outbreak on the Diamond Princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures

Rocklöv, J; Sjödin, H; Wilder-Smith, A

Cruise ships carry a large number of people in confined spaces with relative homogeneous mixing over a period of time that is longer than for any other mode of transportation. 1 Thus, cruise ships present a unique environment for transmission of human-to-human transmitted infections. The association of acute respiratory infections (ARI) incidence in passengers is statistically significant with season, destination and duration of travel. 2 In February 2012, an outbreak of respiratory illness occurred on the cruise ship off Brazil, resulting in 16 hospitalizations due to severe ARI and one death. 3 In May 2020, a dual outbreak of pandemic (H1N1) 2009 and influenza A (H3N2) on a cruise ship occurred: of 1,970 passengers and 734 crew members, 82 (3.0%) were infected with pandemic (H1N1) 2009 virus, and 98 (3.6%) with influenza A (H3N2) virus. 4 Four subsequent cases were epidemiologically linked to passengers but no evidence of sustained transmission to the community or passengers on the next cruise was reported. 4 In September 2000 an outbreak of influenza-like illness was reported on a cruise ship sailing off the Australian coast with over 1,100 passengers and 400 crew on board, coinciding with the peak influenza period in Sydney. 5 The cruise morbidity was high with 40 passengers hospitalized, two of whom died. A total of 310 passengers (37%) reported suffering from an influenza-like illness.