Participants
Inclusion criteria is a child aged 7-18 years old, previously diagnosed
with COVID-19 infection by an evidence of viral antigen detection
between 1-6 months prior to the study, and the child must be able to
perform acceptable spirometry in accordance with the American Thoracic
Society (ATS) / European Respiratory Society (ERS)
criteria8. Exclusion criteria is any of the
followings; 1) a history of smoking, 2) respiratory infection within
four weeks prior to the assessment, 3) using corticosteroids within four
weeks prior to the assessment, and 4) presence of other medical
conditions that may affect pulmonary function, including asthma,
restrictive lung diseases and neuromuscular weakness. Children who met
the criteria were invited to participate in this study via telephone.