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. 2021 Apr:34:100807.
doi: 10.1016/j.eclinm.2021.100807. Epub 2021 Mar 29.

The impact of the lockdown and the re-opening of schools and day cares on the epidemiology of SARS-CoV-2 and other respiratory infections in children - A nationwide register study in Finland

Marjut Haapanen  1 , Marjo Renko  1   2   3 , Miia Artama  4   5 , Ilari Kuitunen  1   6
Affiliations

The impact of the lockdown and the re-opening of schools and day cares on the epidemiology of SARS-CoV-2 and other respiratory infections in children - A nationwide register study in Finland

Marjut Haapanen et al. EClinicalMedicine. 2021 Apr.

Abstract

Background: Nationwide restrictions started in Finland in March to prevent the spread of COVID-19, leading to school and day care closures. The aim of this study is to describe the effect of closures and re-openings on the respiratory pathogen epidemiology.

Methods: Laboratory-confirmed cases of SARS-CoV-2; respiratory syncytial virus (RSV); influenza (A & B); parainfluenza-, adeno-, and rhinoviruses; Mycoplasma pneumoniae; and Streptococcus pneumoniae in children were collected from the National Infectious Disease Register over the period of 2017-2020. Weekly incidences (weeks 1 to 35) with 95% confidence intervals (CIs) were calculated per 100 000 children in 2020 and compared by incidence rate ratios (IRRs) to corresponding periods in 2017-2019.

Findings: The lockdown had immediate impact on the incidences of respiratory pathogens except SARS-CoV-2. Week after the lockdown began IRR was 0•3 (CI 0•3-0•4) and next week the IRR was 0•1 (0•1-0•2). The incidence of SARS-CoV-2 started to decline eight weeks after the lockdown began. The highest recorded weekly incidence of SARS-CoV-2 was 7•2/100 000 children. The effect of the lockdown lasted until late summer. Rhinovirus and SARS-CoV-2 began to increase before the schools or day cares opened in August. The re-opening of schools seemed to have no impact on the incidence of any pathogen.

Interpretation: Our results suggest that general social distancing, including school and day care closures, played a crucial role in reducing infections, and the effect lasted for several weeks. The re-opening of schools and day care centres seems to have had no immediate impact on the incidences of any respiratory pathogens.

Funding: This study had no funding source.

Keywords: COVID-19; Public health; Register study; Social distancing.

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Conflict of interest statement

None of the authors have any potential competing interests to declare.

Figures

Fig. 1
Fig. 1
Incidences of laboratory-confirmed respiratory pathogens in relation to school and day care closures and summer vacation among 0-to-14-year-old patients. SARS-CoV-2 infections among 0-to-19-year-old patients. The grey area presents the numbers of weekly SARS-CoV-2 PCR tests performed in Finland on patients of all ages. Pink boxes indicate the school and day care closures in the spring and summer vacation periods.
Fig. 2
Fig. 2
Weekly incidences of respiratory pathogens in 2020 in comparison to mean weekly incidences from 2017 to 2019. Children aged 0–14 years are included, and for SARS-CoV-2, children aged 0–19 years are included in the analysis. Pink boxes indicate the school and day care closures in the spring and summer vacation periods.
Fig. 3
Fig. 3
Weekly incidences of respiratory pathogens per 100 000 children grouped by age in 2020. Age groups are 0–4, 5–9 and 10–14 years for RSV; influenza (A & B); parainfluenza-, adeno-, and rhinoviruses; Mycoplasma pneumoniae; and Streptococcus pneumoniae. SARS-CoV-2 grouped to 0–9 and 10–19 years due to register design. Pink boxes indicate the school and day care closures in the spring and summer vacation periods.
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