School holidays and respiratory syncytial virus transmission in Sweden: An interrupted time series analysis

Acta Paediatr. 2024 Sep;113(9):2081-2090. doi: 10.1111/apa.17313. Epub 2024 Jun 7.

Abstract

Aim: Respiratory syncytial virus (RSV) represents a significant cause of morbidity for children worldwide, especially for newborns. As RSV vaccines are not routinely used for children yet, non-pharmaceutical interventions (NPIs) represent the main strategy for prevention. The objective of this study was to investigate the correlation between school holidays and RSV transmission.

Methods: Data were collected from the weekly reports on RSV incidence for the 2021/2022 and 2022/2023 seasons in Sweden. The 7-day cumulative incidence of RSV was compared before and after the designated school holidays (Fall, Christmas, and Winter holidays).

Results: Our findings reveal an immediate (-1.7%, p < 0.001, 95% CI [-3.1%, -0.4%]) and gradual (-1.4%/week, p < 0.001, 95%CI [-1.8, -1.0]) reduction in RSV incidence following the Fall holiday in 2021, especially among children under 1 year of age, both immediately (-107.6%, p < 0.05, 95% CI [-203.7, -11.5]) and gradually afterwards (-58.5%/week, p < 0.001, 95% CI [-72.7, -44.3]). Mixed results were obtained for the Fall in 2022/2023 and for the Winter and holidays in both the studied years.

Conclusions: While the Fall holiday in 2021/2022 was associated with a decrease in RSV incidence in Sweden, our results do not support a universal effect of school holidays on reducing RSV transmission.

Keywords: RSV; bronchiolitis; child health; public health.

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • Female
  • Holidays*
  • Humans
  • Incidence
  • Infant
  • Infant, Newborn
  • Interrupted Time Series Analysis*
  • Male
  • Respiratory Syncytial Virus Infections* / epidemiology
  • Respiratory Syncytial Virus Infections* / prevention & control
  • Respiratory Syncytial Virus Infections* / transmission
  • Schools*
  • Seasons
  • Sweden / epidemiology