Estimation of the infection fatality rate and the total number of SARS-CoV-2 infections

  1. Carlos Hernandez-Suarez
  2. Paolo Verme
  3. Efren Murillo-Zamora

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Abstract

We introduce a simple methodology to estimate the infection fatality rate (IFR) and from here the total number of infected with SARS-CoV-2. The virus has shown to be highly infectious and thus we based our method under the assumption that all members of a household with at least one confirmed case of COVID-19 should be infected, therefore we estimate the IFR using the number of secondary fatalities in households. The simplicity of the methodology allows for large sample sizes, since it requires minimal laboratory testing capabilities. We applied this methodology to a database of 3,232 confirmed cases in Mexico and arrived to an IFR estimate within the range reported in other studies.

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  1. ScreenIT

    SciScore for 10.1101/2020.04.24.20075291: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    SARS-CoV-2 IgG and IgM antibodies were tested on EDTA plasma or whole blood by a lateral flow test according to the manufacturer’s recommendations (IgM/IgG Antibody to SARS-CoV-2 lateral flow test, Livzon Diagnostics Inc.
    IgM
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistics: Statistical analysis was performed in RStudio 1.2 and R 3.6.0.
    RStudio
    suggested: (RStudio, RRID:SCR_000432)

    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:
    The low IFR is encouraging, but several caveats exist. Although blood donors represent a very broad population base, they are selected healthy and self-defer for two weeks after signs of COVID-19. Conversely, blood donor prevalence increases with income7 and we speculate that this leads to higher risk of exposure through travel and social activity. We may therefore either under or overestimate the true population immunity. We validated the antibody assay primarily in individuals diagnosed with clinical COVID-19. If silent and mild infections lead to weaker antibody responses, we will underestimate the population immunity. Also, screening only for antibodies may underestimate the prevalence of infections, if cellular cytotoxicity is able to eradicate virally infected cells, as for SARS-CoV, before eliciting a humoral response8. Finally, this study only addresses the IFR in 17–69-year-old individuals. The IFR in other population strata, e.g. among individuals above 80 or with comorbidity is higher6,9. Currently, the governments in most countries are trying to balance the economic consequences of a societal lockdown against the risk of an uncontrolled epidemic. Our results underpin that social distancing in a healthy population predominately acts as a means to protect vulnerable individuals. It would be challenging to perform an unbiased seroprevalence survey in the background population. As blood donation facilities are located nationwide and operate continuously the screening ...

    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 rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  2. Version published to 10.1101/2020.04.23.20077446v4 on medRxiv
  3. Version published to 10.1101/2020.04.23.20077446v3 on medRxiv
  4. Version published to 10.1101/2020.04.23.20077446v2 on medRxiv
  5. Version published to 10.1101/2020.04.23.20077446v1 on medRxiv