Methods
This prospective cohort, within a nested case-control study, included all children consecutively tested with reverse-transcriptase polymerase chain reaction (RT-PCR) for SARS-CoV-2 from nasopharyngeal/oropharyngeal samples collected at RCH between 1st March and 31st October 2020. SARS-CoV-2 positive (SARS-CoV-2[+]) children were age and sex-matched to consecutively tested SARS-CoV-2 negative (SARS-CoV-2[-]) controls at a ratio of 1:2. Negative controls used for matching were chosen using the following sequential criteria; (1) nearest chronological swab, (2) closest age match and (3) gender match. Symptom data and past medical history was obtained via a questionnaire completed by the child’s guardian and verified against the participant’s electronic medical record. Cardiac disease was defined as any previously diagnosed congenital heart disease (CHD) ranging from septal defects to cyanotic congenital heart disease. Respiratory disease was defined as previously diagnosed asthma, obstructive sleep apnoea (OSA), bronchopulmonary dysplasia (BPD), cystic fibrosis (CF), primary ciliary dyskinesia (PCD), interstitial lung disease (ILD), bronchiectasis or neuromuscular weakness. This study received ethics approval from the RCH Human Research Ethics Committee (HREC #37024).
Descriptive statistics were used to summarise the cohort characteristics. Median and inter-quartile ranges were reported as data were non-parametric. Statistical analysis was performed using Stata Version 16.0 (Stata Corporation, College Station, Texas, USA). Pearson’s chi-square test was used for comparison of categorical variables.