Speaker
Description
School closures were among the most contentious non-pharmaceutical interventions during the pandemic due to their socio-economic costs and uncertainty surrounding their population-level epidemiological impact. Given the role of schools as key transmission settings, we retrospectively assessed their effect on SARS-CoV-2 dynamics in Portugal prior to mass vaccination.
We used an age-structured transmission model fitted to hospitalization and seroprevalence data within a Bayesian framework. We then compared the observed trajectories against two counterfactuals: schools remaining open during the lockdown in spring 2020, and schools closing for in-person education following the summer holidays. Elasticity analyses quantified the contributions of each age group to transmission.
Our results show that the 2020 pandemic in Portugal was primarily adult-driven. Keeping schools open during the first lockdown would have driven hospitalizations far beyond observed levels, unless school contacts reached at most 50% of pre-pandemic levels. In contrast, closing schools after summer, when adult-driven transmission was already high, would not have prevented the autumn wave, though it could have mitigated its impact.
These findings underscore that the epidemiological impact of school closures is highly context-dependent, shaped by within-school mitigation and community transmission. Integrated strategies combining both are essential to effectively curb transmission during future pandemics.
