SARS-CoV-2 infections among Australian passengers on the Diamond Princess cruise ship: A retrospective cohort study

Abstract

Background Prolonged periods of confined living on a cruise ship increase the risk for respiratory disease transmission. We describe the epidemiology and clinical characteristics of a SARS-CoV-2 outbreak in Australian passengers on the Diamond Princess cruise ship and provide recommendations to mitigate future cruise ship outbreaks. Methods We conducted a retrospective cohort study of Australian passengers who travelled on the Diamond Princess from 20 January until 4 February 2020 and were either hospitalised, remained in Japan or repatriated. The main outcome measures included an epidemic curve, demographics, symptoms, clinical and radiological signs, risk factors and length of time to clear infection. Results Among 223 Australian passengers, 56 were confirmed SARS-CoV-2 positive. Forty-nine cases had data available and of these over 70% had symptoms consistent with COVID-19. Of symptomatic cases, 17% showed signs and symptoms before the ship implemented quarantine and a further two-thirds had symptoms within one incubation period of quarantine commencing. Prior to ship-based quarantine, exposure to a close contact or cabin mate later confirmed SARS-CoV-2 positive was associated with a 3.78 fold (95% CI, 2.24–6.37) higher risk of COVID-19 acquisition compared to non-exposed passengers. Exposure to a positive cabin mate during the ship’s quarantine carried a relative risk of 6.18 (95% CI, 1.96–19.46) of developing COVID-19. Persistently asymptomatic cases represented 29% of total cases. The median time to the first of two consecutive negative PCR-based SARS-CoV-2 assays was 13 days for asymptomatic cases and 19 days for symptomatic cases (p = 0.002). Conclusion Ship based quarantine was effective at reducing transmission of SARS-CoV-2 amongst Australian passengers, but the risk of infection was higher if an individual shared a cabin or was a close contact of a confirmed case. Managing COVID-19 in cruise ship passengers is challenging and requires enhanced health measures and access to onshore quarantine and isolation facilities.

Transmission of SARS-CoV-2 Associated with Cruise Ship Travel: A Systematic Review

“…We excluded 53 studies (see Supplementary Materials File S3 and File S4 for the reasons for exclusion). In total, we included 26 articles: 2 environmental studies [ 15 , 16 ], 23 papers considering transmission of SARS-CoV-2 aboard cruise ships [ 6 , 7 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], and one systematic review [ 38 ] ( Supplementary Materials File S5 ). The main characteristics of the included studies are presented in Table 1 and Table 2 .…”

“…Among 23 papers reporting on onboard transmission of SARS-CoV-2, 15 articles presented different aspects of the outbreak on the Diamond Princess (DP) cruise ship [ 7 , 17 , 19 , 20 , 21 , 23 , 24 , 25 , 26 , 27 , 29 , 30 , 31 , 35 , 37 ]. Nine articles reported on other international ships [ 6 , 7 , 18 , 22 , 28 , 32 , 33 , 34 , 36 ].…”

“…Six studies reporting on the DP outbreak presented data focusing on repatriated citizens from the US [ 7 , 26 , 29 ], Hong Kong [ 21 ], Israel [ 17 ], and Australia [ 35 ]. Although there were similarities between results of the studies on the US repatriated citizens [ 7 , 26 , 29 ], there were also some notable discrepancies, including the number of repatriated citizens, the number of SARS-CoV-2 cases, and importantly, the number of symptomatic and asymptomatic cases ( Supplementary Materials File S6 ).…”

Development of a mathematical model to predict the health impact and duration of SARS-CoV-2 outbreaks on board cargo vessels

“…The spread of infectious diseases amongst crew on board cargo vessels is facilitated by several factors including a high population density in frequent direct contact areas, sharing of general amenities on board (Codreanu et al 2021b ; World Health Organization 2020a ), and interactions with shore-based maritime workers. Risk mitigation through international sanitation legislation requirements (World Health Organization 2011a , b ; 2016 ; EU EUSHIPSAN Act Joint Action 2016 ; World Health Organization 2005 ) and the measures mandated under the International Health Regulations (Codreanu et al 2021b ; Rocklöv et al 2020 ; Tabata et al 2020 ; Nakazawa et al 2020 ) have decreased the transmissions of SARS-CoV-2 (Codreanu et al 2021a , b ; Rocklöv et al 2020 ), but were unable to fully control outbreaks on board (Codreanu and Armstrong 2021 ; Codreanu et al 2021a ; Walker et al 2021 ).…”

Development of a mathematical model to predict the health impact and duration of SARS-CoV-2 outbreaks on board cargo vessels

“…The spread of infectious diseases amongst crew on board cargo vessels is facilitated by several factors including a high population density in frequent direct contact areas, sharing of general amenities on board (Codreanu et al, 2021b; World Health Organization, 2020a), and interactions with shore-based maritime workers. Risk mitigation through international sanitation legislation requirements (World Health Organization, 2011a,b, 2016; EU SHIPSAN Act Joint Action, 2016; World Health Organization, 2005) and the measures mandated under the International Health Regulations (Codreanu et al, 2021b; Rocklöv et al, 2020; Tabata et al, 2020; Nakazawa et al, 2020) have decreased the transmissions of SARS-CoV-2 (Codreanu et al, 2021b,a; Rocklöv et al, 2020), but were unable to fully control outbreaks on board (Codreanu and Armstrong, 2021; Codreanu et al, 2021a; Walker et al, 2021).…”