Background: Many countries reported missing and atypical influenza and RSV seasons during the COVID-19 pandemic. Here we describe the incidence and seasonality of COVID-19, influenza, and RSV hospitalizations in Norway between 2017 and 2024, and the disease burden between 2022 and 2024.
Methods: Using nationwide data on ICD-10 discharge codes, procedure codes and laboratory results, we calculate the incidence of COVID-19, influenza, and RSV hospitalizations, by age group, week and surveillance year between January 2017 to April 2024, and report proportions receiving intensive care, deaths and length of stay between 2022 and 2024.
Results: The transmission of influenza and RSV was interrupted the first year of the COVID-19 pandemic and reemerged with epidemics outside of the normal seasonality in 2021/2022, after COVID-19 restrictions were removed. Between 2022 and 2024, COVID-19 was a greater contributor to hospitalizations than influenza and RSV, with higher mortality rate within two weeks of admission. The use of ventilatory support/intensive care admission was highest among patients hospitalized with RSV.
Conclusion: The transmission of influenza and RSV was interrupted during the first year of the COVID-19 pandemic, followed by an unusual seasonality. Although many hospitalizations are caused by RSV and influenza, COVID-19 was the largest contributor of these three to hospital burden in the first years with co-circulation.
Keywords: COVID-19; Disease Burden; Influenza; Length of stay; RSV, Respiratory Syncytial Virus.
Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.