Childhood Asthma and COVID-19: A Nested Case-Control Study

BackgroundMost pediatric studies of asthma and COVID-19 to date have been ecological, which offer limited insight. We evaluated the association between asthma and COVID-19 at an individual level. MethodsUsing data from prospective clinical registries, we conducted a nested case-control study comparing three groups: children with COVID-19 and underlying asthma ("A+C" cases); children with COVID-19 without underlying disease ("C+" controls); and children with asthma without COVID-19 ("A+" controls). ResultsThe cohort included 142 A+C cases, 1110 C+ controls, and 140 A+ controls. A+C cases were more likely than C+ controls to present with dyspnea and wheezing, to receive pharmacologic treatment including systemic steroids (all p<0.01), and to be hospitalized (4.9% vs 1.7%, p=0.01). In the adjusted analysis, A+C cases were nearly 4 times more likely to be hospitalized than C+ controls (adjusted OR=3.95 [95%CI=1.4-10.9]); however, length of stay and respiratory support level did not differ between groups. Among A+C cases, 8.5% presented with an asthma exacerbation and another 6.3% developed acute exacerbation symptoms shortly after testing positive for SARS-CoV-2. Compared to historic A+ controls, A+C cases had less severe asthma, were less likely to be on controller medications, and had better asthma symptom control (all p<0.01). ConclusionsIn our cohort, asthma was a risk factor for hospitalization in children with COVID-19, but not for worse COVID-19 outcomes. SARS-CoV-2 does not seem to be a strong trigger for pediatric asthma exacerbations. Asthma severity was not associated with higher risk of COVID-19. Key messagesIn this pediatric cohort, asthma was a risk factor for hospitalization in children with COVID-19, but not for worse COVID-19 outcomes. Baseline asthma severity was not associated with higher risk of COVID-19, and SARS-CoV-2 did not seem to be a strong trigger for pediatric asthma exacerbations.