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A SARS-CoV-2 Omicron outbreak among crew members on a cruise ship in Germany in early 2022
Affiliations- Division of Hygiene and Infectious Diseases, Institute for Hygiene and Environment, Hamburg, Germany
- Postgraduate Training for Applied Epidemiology, Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
- European Centre for Disease Prevention and Control Fellowship Programme, Field Epidemiology Path, Stockholm, Sweden
- Hamburg Port Health Centre, Institute for Hygiene and Environment, Hamburg, Germany
- Responsible Ship Physician, Germany
- Next-Generation Sequencing Laboratory, Institute for Hygiene and Environment, Hamburg, Germany
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Abstract
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks on cruise ships
have rarely been investigated. In early 2022, we were informed about a SARS-CoV-2 outbreak on a cruise
ship calling Port of Hamburg after 10 infections among crew members were detected. We conducted an
outbreak investigation in collaboration between ship owners, the ship physician and Hamburg’s Institute
for Hygiene and Environment, to identify risk factors and to achieve containment. The aim was to identify
risk factors for SARS-CoV-2 infection and SARS-CoV-2 variants in a cohort of 165 crew members.
Materials and methods: For this purpose, we collected data on age, sex, nationality, boarding-time, cabin use
(single/shared), work place, and vaccination status of the study participants. Cases were defined as individuals
who tested SARS-CoV-2 positive at least once in daily screenings during the outbreak period (10 days)
by polymerase chain reaction or antigen test. We investigated risk factors for infection by descriptive, univariable
and multivariable analysis. We performed whole genome sequencing to identify SARS-CoV-2 variants.
Results: We verified 103 SARS-CoV-2 positive cases (attack rate [AR] 62.4%); 39/41 sequenced samples
were BA.2.3 Omicron subtype, one BA.1 and one BA.1.1. Among boostered crew members, AR was 38%
vs. 65% among those vaccinated once or twice. Among those who stayed < 30 days on board, AR was
31% vs. 72% among those staying on board longer. Among Europeans, the AR was 53% vs. 71% in non-
-Europeans. Adjusting for age and sex, cases were more likely to have received no booster vaccine (odds
ratio [OR]: 2.66, 95% confidence interval [CI]: 0.99–7.13), to have spent more time on board (≥ 30 days,
OR: 6.36, 95% CI: 2.81–14.40 vs. < 30 days) and to have a non-European nationality (OR: 2.14, 95% CI:
1.08–4.27). The outbreak stopped shortly after offboard isolation of cases.
Conclusions: This investigation confirms the importance of a booster vaccine against COVID-19. Longer
stays onboard could facilitate social mixing. Further studies could investigate the impact of social, cultural/
behavioural patterns and public health access on the infection risk. Physical distancing together with
screening and isolation can contain SARS-CoV-2 outbreaks on cruise ships.
Abstract
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks on cruise ships
have rarely been investigated. In early 2022, we were informed about a SARS-CoV-2 outbreak on a cruise
ship calling Port of Hamburg after 10 infections among crew members were detected. We conducted an
outbreak investigation in collaboration between ship owners, the ship physician and Hamburg’s Institute
for Hygiene and Environment, to identify risk factors and to achieve containment. The aim was to identify
risk factors for SARS-CoV-2 infection and SARS-CoV-2 variants in a cohort of 165 crew members.
Materials and methods: For this purpose, we collected data on age, sex, nationality, boarding-time, cabin use
(single/shared), work place, and vaccination status of the study participants. Cases were defined as individuals
who tested SARS-CoV-2 positive at least once in daily screenings during the outbreak period (10 days)
by polymerase chain reaction or antigen test. We investigated risk factors for infection by descriptive, univariable
and multivariable analysis. We performed whole genome sequencing to identify SARS-CoV-2 variants.
Results: We verified 103 SARS-CoV-2 positive cases (attack rate [AR] 62.4%); 39/41 sequenced samples
were BA.2.3 Omicron subtype, one BA.1 and one BA.1.1. Among boostered crew members, AR was 38%
vs. 65% among those vaccinated once or twice. Among those who stayed < 30 days on board, AR was
31% vs. 72% among those staying on board longer. Among Europeans, the AR was 53% vs. 71% in non-
-Europeans. Adjusting for age and sex, cases were more likely to have received no booster vaccine (odds
ratio [OR]: 2.66, 95% confidence interval [CI]: 0.99–7.13), to have spent more time on board (≥ 30 days,
OR: 6.36, 95% CI: 2.81–14.40 vs. < 30 days) and to have a non-European nationality (OR: 2.14, 95% CI:
1.08–4.27). The outbreak stopped shortly after offboard isolation of cases.
Conclusions: This investigation confirms the importance of a booster vaccine against COVID-19. Longer
stays onboard could facilitate social mixing. Further studies could investigate the impact of social, cultural/
behavioural patterns and public health access on the infection risk. Physical distancing together with
screening and isolation can contain SARS-CoV-2 outbreaks on cruise ships.
Keywords
crew, cruise ship, Omicron, outbreak, SARS-CoV-2
About this articleTitle
A SARS-CoV-2 Omicron outbreak among crew members on a cruise ship in Germany in early 2022
Journal
Issue
Article type
Original article
Pages
235-242
Published online
2023-12-15
Page views
487
Article views/downloads
131
DOI
10.5603/imh.96935
Pubmed
Bibliographic record
IMH 2023;74(4):235-242.
Keywords
crew
cruise ship
Omicron
outbreak
SARS-CoV-2
Authors
Silja Bühler
Philip Busch
Philip Wittkamp
Katharina Alpers
Achim Doerre
Anita Plenge-Bönig
Janine Fornaçon
Christian Schäfers
Anne Reichstein
Birgit Grassl
Elisabeth Hewelt
Martin Dirksen-Fischer
Scarlett Kleine-Kampmann
References (21)- Guagliardo SA, Prasad PV, Rodriguez A, et al. Cruise ship travel in the era of coronavirus disease 2019 (COVID-19): a summary of outbreaks and a model of public health interventions. Clin Infect Dis. 2022; 74(3): 490–497.
- Moriarty LF, Plucinski MM, Marston BJ, et al. Public health responses to COVID-19 outbreaks on cruise ships - Worldwide, February-March 2020. MMWR Morb Mortal Wkly Rep. 2020; 69(12): 347–352.
- Bert F, Scaioli G, Gualano MR, et al. Norovirus outbreaks on commercial cruise ships: a systematic review and new targets for the public health agenda. Food Environ Virol. 2014; 6(2): 67–74.
- Kordsmeyer AC, Mojtahedzadeh N, Heidrich J, et al. Systematic review on outbreaks of SARS-CoV-2 on cruise, navy and cargo ships. Int J Environ Res Public Health. 2021; 18(10).
- Kak V. Infections on cruise ships. Microbiol Spectr. 2015; 3(4).
- Acevedo F, Diskin AL, Dahl E. Varicella at sea: a two-year study on cruise ships. Int Marit Health. 2011; 62(4): 254–261.
- Rocklöv J, Sjödin H, Wilder-Smith A. COVID-19 outbreak on the Diamond Princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures. J Travel Med. 2020; 27(3).
- Rosca EC, Heneghan C, Spencer EA, et al. Transmission of SARS-CoV-2 associated with cruise ship travel: a systematic review. Trop Med Infect Dis. 2022; 7(10).
- Zhang Hu, Wang Q, Chen J, et al. Cruise tourism in the context of COVID-19: Dilemmas and solutions. Ocean Coast Manag. 2022; 228: 106321.
- Gravningen K, Henriksen S, Hungnes O, et al. Risk factors, immune response and whole-genome sequencing of SARS-CoV-2 in a cruise ship outbreak in Norway. Int J Infect Dis. 2022; 118: 10–20.
- Gesetz zur Durchführung der Internationalen Gesundheitsvorschriften (2005). 2013. www.gesetze-im-internet.de/igv-dg (cited 2023 May 23).
- Hecht J, Reichert F, Suwono B, et al. COSIK – COVID-19-Surveillance in Krankenhäusern. Epidemiologisches Bulletin. 2022; 2: 19–28.
- Barda N, Dagan N, Cohen C, et al. Effectiveness of a third dose of the BNT162b2 mRNA COVID-19 vaccine for preventing severe outcomes in Israel: an observational study. Lancet. 2021; 398(10316): 2093–2100.
- Li H, Durbin R. Fast and accurate short read alignment with Burrows-Wheeler transform. Bioinformatics. 2009; 25(14): 1754–1760.
- Li H, Handsaker B, Wysoker A, et al. The Sequence Alignment/Map format and SAMtools. Bioinformatics. 2009; 25(16): 2078–2079.
- Broadinstitute. Picard. A set of command line tools (in Java) for manipulating high-throughput sequencing (HTS) data and formats such as SAM/BAM/CRAM and VCF. http://broadinstitute.github.io/picard/.
- Pangolin. Software package for assigning SARS-CoV-2 genome sequences to global lineages. https://github.com/cov-lineages/pangolin (cited 2023 May 23).
- Snippy. Rapid haploid variant calling and core genome alignment. https://github.com/tseemann/snippy (cited 2023 May 23).
- SnippySnake. Variant calling pipeline with snippy. https://gitlab.com/bfr_bioinformatics/snippySnake (cited 2023 May 23).
- Robert Koch Institut. Quarantäne- und Isolierungsdauern bei SARS-CoV-2-Expositionen und -Infektionen entsprechend dem Beschluss der Ministerpräsidentenkonferenz vom 7. und 24. Januar 2022. https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Quarantaene/Absonderung-Archiv.html (cited 2022 June 18).
- Kumar S, Karuppanan K, Subramaniam G. Omicron (BA.1) and Sub-Variants (BA.1, BA.2 and BA.3) of SARS-CoV-2 spike infectivity and pathogenicity: a comparative sequence and structural-based computational assessment. J Med Virol. 2022; 94(10): 4780–4791.
