Analysing different exposures identifies that wearing masks and establishing COVID-19 areas reduce secondary-attack risk in aged-care facilities

  1. Bastien Reyné
  2. Christian Selinger
  3. Mircea T Sofonea
  4. Stéphanie Miot
  5. Amandine Pisoni
  6. Edouard Tuaillon
  7. Jean Bousquet
  8. Hubert Blain
  9. Samuel Alizon

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Abstract

Background

The COVID-19 epidemic has spread rapidly within aged-care facilities (ACFs), where the infection-fatality ratio is high. It is therefore urgent to evaluate the efficiency of infection prevention and control (IPC) measures in reducing SARS-CoV-2 transmission.

Methods

We analysed the COVID-19 outbreaks that took place between March and May 2020 in 12 ACFs using reverse transcription–polymerase chain reaction (RT–PCR) and serological tests for SARS-CoV-2 infection. Using maximum-likelihood approaches and generalized linear mixed models, we analysed the proportion of infected residents in ACFs and identified covariates associated with the proportion of infected residents.

Results

The secondary-attack risk was estimated at 4.1%, suggesting a high efficiency of the IPC measures implemented in the region. Mask wearing and the establishment of COVID-19 zones for infected residents were the two main covariates associated with lower secondary-attack risks.

Conclusions

Wearing masks and isolating potentially infected residents appear to be associated with a more limited spread of SARS-CoV-2 in ACFs.

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  1. Version published to 10.1093/ije/dyab121
  2. ScreenIT

    SciScore for 10.1101/2020.11.27.20239913: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: This observational study was approved by the Internal Review Board from the Montpellier University Hospital (IRB-MTP_2020_06_202000534).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Blood testing for IgG antibodies directed against the SARS-CoV-2 nucleocapsid protein used an enzyme-linked immunosorbent assay CE-IVD marked kit (ID screen SARS-CoV-2-N IgG indirect from IDVet, Montpellier, France).
    IgG
    suggested: None
    SARS-CoV-2 nucleocapsid protein
    suggested: (Bioss Cat# bsm-41414M, RRID:AB_2848129)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This was motivated by the fact that early guidelines led to contact limitations in NH (e.g. cancellation of group events, or assignment of members of the staff to specific floors). We found that two factors affected the epidemic spread within the NHs: the delay in mask-wearing and the reported mask availability. The earlier mask-wearing was generalised in the NH, the smaller the outbreak. Unexpectedly, reporting a lower mask availability was associated with fewer outbreaks. While this effect should be handled with care because of the subjective dimension of the variable, an explanation could be that a (reported) shortage of masks occurred in the NHs that were using more masks. Interestingly, when using less detailed statistical models that ignored the floor structure (i.e. GLMs), therefore assuming that cases occurred homogeneously in the NH, the main effect we found was the settingup of a “COVID unit”, which was associated with smaller outbreaks. This further strengthens our choice to use a detailed GLMM model to analyse the data. The presence of temporary agency workers before the first case was also associated with larger outbreaks in some of the GLMs. One potential limitation of the analysis could be the presence of over-dispersion in the data. When correcting for this potential bias, only 9 of the 127 potential GLMMs had a significant factor, which was the presence of a COVID-unit in the NH. Unfortunately, correcting for overdispersion requires the use of quasi-likclihoo...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  3. Version published to 10.1101/2020.11.27.20239913v1 on medRxiv