Description of the study population
In the total study population, the mean age of the participants was 7.4 years and a minority were girls (38.7%) (Table 1). Regarding the socio-demographic status, 15.0% were living with a single parent with a divorce rate of 29.2%. These two variables were the lowest in 2020 and the highest in 2018 (2.8% and 22.2% vs. 25% and 37.5%, respectively). Additionally, 31.5% of our study population was exposed to tobacco smoke, while the year 2021 had the lowest percentage of exposure (25%). The majority of patients (70.2%) had a clinically diagnosed viral infection. This percentage was the highest in 2018 (87.5%), followed by 2021 (72.9%), 2020 (69.4%), and 2019 (53.7%). However, not all of these clinical diagnoses were confirmed by a nasal or throat swab with the highest load of testing being taken in 2020 and 2021. Regarding missing data, there were no missing variables for age and sex, and for the remaining variables the percentage of missing data did not exceed 8.9%, except for secondhand smoke exposure, which was missing for 24.7%.