Study design and participants
This is a cross-sectional study conducted in two different periods, the first from April 19 to June 21, 2022, and the second from November 8 to December 21, 2022. The main outcome of the study was the absence of the child from attending the school in person due to RTI or other non-respiratory medical causes.
The study population was composed of 253 students (4-11 years) belonging to 20 classrooms, 11 in spring 2022 and 9 in autumn 2022, attending 4 and 16 classrooms of preschool (4 to 5 years-old) and primary school (6 to 11 years-old) stages, respectively. A written informed consent was previously obtained from parents or guardians of children.