Vaccine efficacy against the SARS-CoV-2 Delta variant during a COVID-19 outbreak aboard a military ship

Correspondence to Dr F de Laval, French Armed Forces Center for Epidemiology and Public Health, French Military Health Service, Paris, Île-de-France, France; f_de_laval@hotmail.com Nowadays, vaccination has become the main tool in the strategy to fight COVID-19 as it reduces the severity of the dise...

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Bibliographic Details
Published in:BMJ military health 2024-02, Vol.170 (1), p.91-92
Main Authors: Maugey, Nancy, Lefebvre, T, Tournier, J-N, Neulat-Ripoll, F, Chapus, C, Grandperret, V, Raynaud, F, Letois, F, Dutasta, F, Janvier, F, Wolf, A, de Laval, F
Format: Article
Language:English
Subjects:
Coronaviruses
COVID-19
COVID-19 - prevention & control
COVID-19 vaccines
Disease transmission
Epidemics
EPIDEMIOLOGY
Genomes
Humans
Infections
Letter
Military Personnel
Polymerase chain reaction
Public health
SARS-CoV-2
Severe acute respiratory syndrome coronavirus 2
Ships
Vaccine Efficacy
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Summary:Correspondence to Dr F de Laval, French Armed Forces Center for Epidemiology and Public Health, French Military Health Service, Paris, Île-de-France, France; f_de_laval@hotmail.com Nowadays, vaccination has become the main tool in the strategy to fight COVID-19 as it reduces the severity of the disease,1 the infectiousness of infected cases and the circulation of the virus by contributing to achieving herd immunity.2 We report the investigation of a COVID-19 outbreak that occurred among the 91 crew members of a French Navy ship from May to July 2021. RT-PCR: Reverse Transcriptase Polymerase Chain Reaction From a public health point of view, previous immunity led to decreased incidence, which was 67% (eight of 12) for the non-immune, 52% (14 of 27) for recovered individuals and 48% (25 of 52) for those who were vaccinated. [...]it did not prevent viral circulation on board (Rt >1); the reinfection rate was 48.3% (15 of 31), the infection rate among the vaccinated was 48.0% (25 of 52) and vaccine efficacy was 39.4% (95% CI 27.1 to 50.9), lower than the >80% expected.2 The high viral load present in a confined ambient air (highlighted by the detection of SARS-CoV-2 RNA in the air conditioning system) may have been implicated. [...]among vaccinated cases, the low median cycle threshold (Ct) value of the RT-PCR (23) and the high proportion of individuals with symptoms were compatible with their infectiousness.
ISSN:2633-3767
2633-3775
DOI:10.1136/bmjmilitary-2022-002082