Contribution of Schools to Covid-19 Pandemic: Evidence from Czechia

  1. Cyril Brom
  2. Jakub Drbohlav
  3. Martin Šmíd
  4. Milan Zajíček

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Purpose

It is unclear how much opening of schools during Covid-19 pandemic contributes to new SARS-CoV-2 infections among children. We investigated the impact of school opening with various mitigation measures (masks, rotations, mass testing) on growth rate of new cases in child cohorts ranging from kindergartens to upper secondary in Czechia, a country heavily hit by Covid-19, since April 2020 to June 2021.

Methods

Our primary method is comparison of the reported infections in age cohorts corresponding to school grades undergoing different regimes. When there is no opportunity for such a comparison, we estimate corresponding coefficients from a regression model. In both the cases, we assume that district-level infections in particular cohorts depend on the school attendance and the external environment in dependence on the current overall risk contact reduction.

Results

The estimates of in-cohort growth rates were significantly higher for normally opened schools compared to closed schools. When prevalence is comparable in the cohorts and general population, and no further measures are applied, the in-cohort growth reduction for closed kindergartens is 29% (SE=11%); primary: 19% (7%); lower secondary: 39% (6%); upper secondary: 47% (6%). For secondary education, mitigation measures reduce school-related growth 2-6 times.

Conclusion

Considering more infectious SARS-CoV-2 variants and the ‘long covid’ risk, mitigation measures in schools, especially in secondary levels, should be implemented for the next school year. Some infections, however, are inevitable, even in kindergartens (where mitigation measures are difficult to implement) and primary schools (where they may not work due to low adherence).

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2021.09.28.21264244: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: Thank you for sharing your code and data.

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    As in any “natural experiment” study, the general limitation is that the comparison cohorts are not truly randomized. Hence, infection numbers in these cohorts may be differentially influenced by uncontrolled factors. Evidence from other countries could strengthen the reliability of our results. Also, our estimates (Tables 1, 2 and Figure 1) apply to situation without contact restrictions and the same prevalence in and outside the examined cohort; so rather than their value, their ordering and ratios should be interpreted. Nevertheless, our model itself is general and when using actual prevalences and contact restriction, it can predict growth as we did on Figure 2. Magnitudes of these particularized predictions (i.e., on Figure 2) do not differ much from the crude estimates (i.e., those in Tables 1, 2 and on Figure 1). This is because for most of the examined period in Czechia, the higher overall prevalence in the population than in the examined cohorts (except for upper secondary level) had the tendency to counterbalance effects of reduced contacts (Figures S4, S6). In conclusion, our findings indicate that school opening have a notable effect on school-related growth rate of infections, but it can be substantially reduced by means of mitigation measures, especially in secondary education levels. The challenging question remains how to increase safety in kindergartens and primary schools wherein mitigation measures appear to be difficult to implement effectively.

    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.
    • No funding statement was detected.
    • No protocol registration statement was detected.

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

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2021.09.28.21264244v1 on medRxiv