Symptoms of Long-COVID 1-Year after a COVID-19 outbreak among sailors on a French aircraft carrier

OBJECTIVES

While persistent symptoms have been reported after the coronavirus disease-2019 (COVID-19), long-term data on outpatients with mild COVID-19 are lacking. The objective was to describe symptoms persisting for 12 months.

METHODS

This prospective cohort study on 1767 sailors of an aircraft carrier in which a Covid-19 outbreak occurred during a mission in April 2020 described predefined self-reported symptoms of Long-COVID at 6, 9 and 12 months. Logistic-regression analyses were used to identify correlates for Long-COVID at months 6, 9 and 12.

RESULTS

Among the 641 participants, 619 (35%) completed at least one follow-up questionnaire (413 COVID-positive and 206 COVID-negative). Symptoms of Long-COVID were reported by 53.7%, 55.2% and 54.3% of COVID-positive participants vs 31.2%, 23.3% and 40.0% in COVID-negative patients, at 6 (p <.002), 9 (p <.002) and 12 months (p =.13), respectively. The most frequent symptoms reported were concentration and memory difficulties, asthenia and sleep disorders.

CONCLUSION

In this study more than half of COVID-positive outpatients reported persistent symptoms up to 12 months post-quarantine. These findings suggests that all patients, including those with mild disease, can be affected by Long-COVID. A lack of difference at 12 months with COVID-negative patienys prompts caution. The symptoms of Long-COVID are so non-specific that they may be viewed as the consequence of multiple intercurrent factors.

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

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.