Where Birth Month, Sex and Age Matters: The Burden of Severe Respiratory Disease in Danish Children <5 Years, 2016-2022.

Background: In light of the substantial impact that respiratory diseases in young children poses on healthcare systems globally, and in the wake of the recent COVID-19 pandemic, there is a growing urgency to obtain reliable estimates on the burden of respiratory disease.

Objectives: The aim of this study is to quantify the overall burden of respiratory disease requiring hospitalizations and explore the trends in these admissions in Danish children <5 years, January 1, 2016-October 31, 2022.

Methods: The number of hospitalizations attributed to respiratory infections in children <5 years, was extracted from the Danish National Patient Register, and stratified into subgroups based on age, gender and birth month, and presented on a month-to-month basis.

Results: A total of 48,194 children under the age of 5, were hospitalized due to respiratory infections within the study period and the annual hospitalization incidence exhibited a noteworthy variation. Risk factors associated with the highest hospitalization incidence were young age, male gender and in children under 1-year-old, birth months falling in the period of November to January. Younger age and admission during the winter months were linked to longer hospital stays. The seasonal pattern of hospitalizations and the distribution of hospitalizations across various subgroups were greatly influenced by the COVID-19 pandemic.

Conclusion: This study describes and quantifies the importance of factoring in specific child demographics and seasonal variations in hospitalizations when devising preventive healthcare strategies such as the use of monoclonal antibody therapy and vaccines.