The value of universal screening for COVID-19 cases on cruise ships during outbreaks

Objectives: To describe the impact of universal screening for coronavirus disease 2019 (COVID-19) on passengers on cruise ships docking in Sydney, Australia, during 2022 that experienced a significant outbreak of COVID-19. Type of program or service: Cruise ship disease surveillance Methods: Case series, based on analysis of cruise ship voyages where universal screening of passengers was requested by a NSW health authority and undertaken by the cruise ship. Results: Of 111 voyages in 2022, three fit the definition for this study. Universal screening during these voyages resulted in the detection of up to 1.8 times the number of existing COVID-19 cases, increasing attack rates of the three voyages from 14% to 24%; 13% to 28%; and 3% to 8% respectively. Case demographics showed an even gender distribution, with a majority 70 years or older. Asymptomatic case percentage ranged from 2% to 54%, with age and gender not associated with symptomatic status. Almost all cases were reported as being fully vaccinated. Genomic testing of cases showed multiple lineages of COVID-19 circulating in all three voyages. Lessons learnt: Public health authorities, the cruise industry and passengers should be aware that a large number of unidentified cases of COVID-19 may disembark from a cruise ship that has experienced a large outbreak of the virus. These cases can seed the infection into vulnerable communities. Universal screening as part of the response to a significant outbreak will help identify cases and limit the spread of COVID-19.