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. 2022 May;27(21):2100612.
doi: 10.2807/1560-7917.ES.2022.27.21.2100612.

Investigation of a COVID-19 outbreak on the Charles de Gaulle aircraft carrier, March to April 2020: a retrospective cohort study

Franck de Laval  1   2 , Hervé Chaudet  1   3   4 , Olivier Gorgé  5 , Joffrey Marchi  1 , Constance Lacrosse  1 , Aissata Dia  1 , Vanessa Marbac  6 , Bakridine Mmadi Mrenda  1 , Gaëtan Texier  1   3 , Flavie Letois  1 , Charles Chapus  5 , Véronique Sarilar  5 , Jean-Nicolas Tournier  5 , Anthony Levasseur  4   7 , Jacques Cobola  6 , Flora Nolent  5 , Fabien Dutasta  8 , Frédéric Janvier  8 ; PA-CDG COVID-19 investigation group  9 ; Jean-Baptiste Meynard  1   2 , Vincent Pommier de Santi  1   3
Collaborators, Affiliations

Investigation of a COVID-19 outbreak on the Charles de Gaulle aircraft carrier, March to April 2020: a retrospective cohort study

Franck de Laval et al. Euro Surveill. 2022 May.

Abstract

BackgroundSARS-CoV-2 emergence was a threat for armed forces. A COVID-19 outbreak occurred on the French aircraft carrier Charles de Gaulle from mid-March to mid-April 2020.AimTo understand how the virus was introduced, circulated then stopped circulation, risk factors for infection and severity, and effectiveness of preventive measures.MethodsWe considered the entire crew as a cohort and collected personal, clinical, biological, and epidemiological data. We performed viral genome sequencing and searched for SARS-CoV-2 in the environment.ResultsThe attack rate was 65% (1,148/1,767); 1,568 (89%) were included. The male:female ratio was 6.9, and median age was 29 years (IQR: 24-36). We examined four clinical profiles: asymptomatic (13.0%), non-specific symptomatic (8.1%), specific symptomatic (76.3%), and severe (i.e. requiring oxygen therapy, 2.6%). Active smoking was not associated with severe COVID-19; age and obesity were risk factors. The instantaneous reproduction rate (Rt) and viral sequencing suggested several introductions of the virus with 4 of 5 introduced strains from within France, with an acceleration of Rt when lifting preventive measures. Physical distancing prevented infection (adjusted OR: 0.55; 95% CI: 0.40-0.76). Transmission may have stopped when the proportion of infected personnel was large enough to prevent circulation (65%; 95% CI: 62-68).ConclusionNon-specific clinical pictures of COVID-19 delayed detection of the outbreak. The lack of an isolation ward made it difficult to manage transmission; the outbreak spread until a protective threshold was reached. Physical distancing was effective when applied. Early surveillance with adapted prevention measures should prevent such an outbreak.

Keywords: Aircraft Carrier; Outbreak; SARS-CoV-2, COVID-19; Ship, Herd immunity.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Flowchart of the COVID-19 outbreak investigation on the Charles de Gaulle aircraft carrier, April 2020
Figure 2
Figure 2
A. Epidemiological curve of confirmed COVID-19 cases according to date of symptom onset and B. Instantaneous reproduction rate curve of the Charles de Gaulle aircraft carrier, April 2020 (n = 959a)
Figure 3
Figure 3
Chord diagram between sleeping compartments and work areas of COVID-19- confirmed cases, Charles de Gaulle aircraft carrier, April 2020 (n = 1,064)
Figure 4
Figure 4
Maximum likelihood tree inferred from sequenced SARS-CoV-2 genomes, Charles de Gaulle aircraft carrier, April 2020 (n = 51), and the French SARS-CoV-2 sequences present in the GISAID database, 3 May 2020 (n = 246)
See this image and copyright information in PMC

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