New research led by UMC Utrecht shows that school closures during a pandemic outbreak are most effective when they are carefully targeted. The study, published in Nature Communications, demonstrates that the right strategy depends on which age groups are driving transmission at different stages of an outbreak. This study provides guidance for authorities, allowing them to make smart and informed decisions regarding school closures in case of a pandemic outbreak.
Closing schools is one of the most difficult decisions during an infectious disease outbreak. While it can help reduce the spread of a virus, it also adversely affects children's education and wellbeing. Researchers from UMC Utrecht, the University of Lisbon and Tilburg University developed a mathematical model to reconstruct how SARS-CoV-2 spread through the population of the Netherlands, including Dutch elementary and secondary schools during the COVID-19 pandemic. By combining epidemiological data with transmission modeling, they were able to evaluate how different school closure and reopening strategies influenced the course of the pandemic.
Transmission changed during the pandemic
The study shows that the age groups responsible for spreading the virus changed over time. At the start of the pandemic, adults contributed most to virus transmission. Later, teenagers became the main drivers, while younger children played a larger role in 2021.
This shift was linked to growing immunity. By 2021, many adults and teenagers had already been infected or vaccinated, making younger children the group that was most susceptible to infection.
As a result, closing secondary schools had the greatest effect on reducing COVID-19 hospital admissions in 2020. At the end of 2021, closing elementary schools became more effective. The findings show that a single approach does not work throughout an outbreak. Instead, interventions should change as the situation changes.
Supporting better public health decisions
The researchers say the study highlights the value of mathematical models for public health policy. During an outbreak, governments often have to act quickly while information is still limited. Models can help predict which measures are likely to have the greatest effect before decisions are made.
"School closures can reduce virus transmission, but they also have major social and educational consequences," says mathematical modeler Ganna Rozhnova PhD , associate professor in the Infectious Disease Modeling Group at UMC Utrecht and senior author of the study. "Our findings show that policymakers can make better decisions by identifying which age groups are driving transmission at different moments during an outbreak. This allows interventions to be more targeted, reducing infections while limiting disruption for children and society."
Preparing for future outbreaks
The researchers will now extend their model to investigate the broader effects of school interventions, including their impact on children's learning and development, and to study how social and demographic differences influence disease spread.
This study is part of the UMC Utrecht modeling group's long-standing research program aimed at improving outbreak preparedness and providing policymakers with robust scientific evidence to support responses to future public health emergencies.
