key: cord-0837372-m5hdaakd
authors: Belavic, Anja; Dimnjakovic, Jelena; Istvanovic, Ana; Svajda, Marija; Poljicanin, Tamara; Pavic Simetin, Ivana
title: Re‐opening schools in Croatia did not have a negative impact on children under 14, but it could not be ruled out in older children
date: 2021-06-29
journal: Acta Paediatr
DOI: 10.1111/apa.16000
sha: 3b04a0cee91e0bf771f7fa6e4c60622dc237a8aa
doc_id: 837372
cord_uid: m5hdaakd

School closures have been used to help tackle COVID-19. Meta-analyses and reviews suggest that children are unlikely to be the main drivers of the pandemic and that opening schools and kindergartens is unlikely to increase COVID-19 mortality rates in older people.1 Croatia closed its schools on 16 March 2020 and they reopened in week 37, 7 September 2020, after the summer holidays. Public Health guidelines for the reopening included mandatory hand hygiene and face masks for children grades 5 (10/11 year olds) and above. Schools were also told to adopt other social distancing measures, including staggered arrival and departure times and student bubbles.

School closures have been used to help tackle COVID-19. Metaanalyses and reviews suggest that children are unlikely to be the main drivers of the pandemic and that opening schools and kindergartens is unlikely to increase COVID-19 mortality rates in older people. 1 Croatia closed its schools on 16 March 2020, and they reopened in week 37, 7 September 2020, after the summer holidays. Public

Health guidelines for the reopening included mandatory hand hygiene and face masks for children grades 5 (10/11 year olds) and

above. Schools were also told to adopt other social distancing measures, including staggered arrival and departure times and student bubbles. They were also offered three different models for primary and secondary school students: just classroom learning, just distance learning or a mixture of the two. More than 90% of schools chose just classroom learning until the peak of the second wave in mid-December 2020, when schools individually decided based on local epidemiologic situations for one of the other two options: mixed or distance.

This study investigated the effect that opening schools in week 37 had on incidence trends from weeks 32-42, by analysing COVID-19 testing data using joinpoint regression. The dependent variable (crude age-specific rate) was calculated by the program from age and time specific counts and population estimates at the end of 2019. The independent variable was time (week), which was treated like continuous variable. Logarithmic transformation was applied, with the statistical significance for the age-specific average During the study period, 20,106 children tested positive, increasing from 343 to 5,031 per week over the study period. The age-specific rates ranged from 0/1000 for students aged 7-14 years in week 32 to 1.86/1000 for those aged 15-19 years in week 42.

The increases in all age groups were 0-6 years (26.0 times), 15-19 (9.3), 20-64 (16.0) and 65 plus (16.4). The age-specific seven-day cumulative incidence rates and trends by age group are presented in Research suggested that opening schools should have had a significant impact on the reproduction number and changes in epidemiologic dynamics after two weeks. 2 However, our study showed no effect on incidence rates in children aged 0-6 years, primary school Another limitation was that we only included cases confirmed with polymerase chain reaction. In order to exclude potential impact of testing capacity on incidence rates we also analysed testing rates between 32 and 42 weeks, APC per week was statistically significant and comparable in all groups, and therefore, any impact would have been uniform.

There were no incidence trend changes associated with children under 14 years of age when schools reopened. Although a negative impact could not be excluded in older children and working populations, it had not spilled over to people aged 66 plus.

Primary schools opening in Croatia were associated with lower total years of life lost, due to reduced educational achievements during closure. 3 

Children are unlikely to be the main drivers of the COVID-19 pandemic -a systematic review

The temporal association of introducing and lifting non-pharmaceutical interventions with the time-varying reproduction number (R) of SARS-CoV-2: a modelling study across 131 countries

Estimation of US children's educational attainment and years of life lost associated with primary school closures during the coronavirus disease 2019 pandemic

The potential impact of the COVID-19 pandemic on child growth and development: a systematic review

School closure and management practices during coronavirus outbreaks including COVID-19: a rapid systematic review