Investigation of a COVID-19 outbreak on the Charles de Gaulle aircraft carrier, March to April 2020: a retrospective cohort study
2022
de Laval, Franck | Chaudet, Hervé | Gorgé, Olivier | Marchi, Joffrey | Lacrosse, Constance | Dia, Aissata | Marbac, Vanessa | Mmadi Mrenda, Bakridine | Texier, Gaëtan | Letois, Flavie | Chapus, Charles | Sarilar, Véronique | Tournier, Jean-Nicolas | Levasseur, Anthony | Cobola, Jacques | Nolent, Flora | Dutasta, Fabien | Janvier, Frédéric | Meynard, Jean-Baptiste | Pommier de Santi, Vincent | Ecosystemes Amazoniens et Pathologie Tropicale (EPat) ; Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Guyane (UG) | Centre d'épidémiologie et de santé publique des armées [Marseille] (CESPA) ; Service de Santé des Armées | Centre Médical Interarmées de Cayenne | Vecteurs - Infections tropicales et méditerranéennes (VITROME) ; Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut de Recherche Biomédicale des Armées [Brétigny-sur-Orge] (IRBA) | Institut Hospitalier Universitaire Méditerranée Infection (IHU Marseille) | Institut de Recherche Biomédicale des Armées [Brétigny-sur-Orge] (IRBA) | Hopital d'instruction des armées Sainte-Anne [Toulon] (HIA) | Sciences Economiques et Sociales de la Santé & Traitement de l'Information Médicale (SESSTIM - U912 INSERM - Aix Marseille Univ - IRD) ; Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM) | Observatoire régional de la santé Provence-Alpes-Côte d'Azur [Marseille] (ORS PACA) | Service de Santé des Armées | Bioinformatique génomique et moléculaire ((U 726)) ; Université Paris Diderot - Paris 7 (UPD7)-Institut National de la Santé et de la Recherche Médicale (INSERM) | Dept. of Organismic and Evolutionary Biology ; Harvard University | MICrobiologie de l'ALImentation au Service de la Santé (MICALIS) ; AgroParisTech-Université Paris-Saclay-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Microbes évolution phylogénie et infections (MEPHI) ; Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS) | Charles de Gaulle Nuclear Aircraft Carrier [Toulon] (CdGNAC)
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Show more [+] Less [-]English. Background SARS-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. Aim To understand how the virus was introduced, circulated then stopped circulation, risk factors for infection and severity, and effectiveness of preventive measures. Methods We 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. Results The 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 (R t ) and viral sequencing suggested several introductions of the virus with 4 of 5 introduced strains from within France, with an acceleration of R t 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). Conclusion Non-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.
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