<p><strong>BACKGROUND: </strong>Respiratory viruses, air pollutants, and aeroallergens are all implicated in worsening pediatric asthma symptoms, but their relative contributions to asthma exacerbations are poorly understood. A significant decrease in asthma exacerbations has been observed during the COVID-19 pandemic, providing a unique opportunity to study how major asthma triggers correlate with asthma activity.</p>

<p><strong>OBJECTIVE: </strong>To determine whether changes in respiratory viruses, air pollutants, and/or aeroallergens during the COVID-19 pandemic were concomitant with decreased asthma exacerbations.</p>

<p><strong>METHODS: </strong>Health care utilization and respiratory viral testing data between January 1st, 2015 and December 31st, 2020 were extracted from the Children's Hospital of Philadelphia (CHOP) Care Network's electronic health record. Air pollution and allergen data were extracted from U.S. Environmental Protection Agency public databases and a National Allergy Bureau-certified station, respectively. Pandemic data (2020) were compared to historical data.</p>

<p><strong>RESULTS: </strong>Recovery of in-person asthma encounters during phased re-opening (June 6 - November 15, 2020) was uneven: primary care well and specialty encounters reached 94% and 74% of pre-pandemic levels, respectively, while primary care sick and hospital encounters reached 21% and 40% of pre-pandemic levels, respectively. During the pandemic, influenza A and influenza B decreased to negligible frequency when compared to pre-pandemic cases, while RSV and rhinovirus infections decreased to low (though non-negligible) pre-pandemic levels, as well. No changes in air pollution or aeroallergen levels relative to historical observations were noted.</p>

<p><strong>CONCLUSIONS: </strong>Our results suggest that viral respiratory infections are a primary driver of pediatric asthma exacerbations. These findings have broad relevance to both clinical practice and the development of health policies aimed at reducing asthma morbidity.</p>

<p><strong>BACKGROUND: </strong>The COVID-19 pandemic caused dramatic changes in daily routines and healthcare utilization and delivery patterns in the United States. Understanding the influence of these changes and associated public health interventions on asthma care is important to determine effects on patient outcomes and identify measures that will ensure optimal future healthcare delivery.</p>

<p><strong>OBJECTIVE: </strong>We sought to identify changes in pediatric asthma-related healthcare utilization, respiratory viral testing, and air pollution during the COVID-19 pandemic.</p>

<p><strong>METHODS: </strong>For the time period Jan 17-May 17, 2015-2020, asthma-related encounters and weekly summaries of respiratory viral testing data were extracted from Children's Hospital of Philadelphia (CHOP) electronic health records, and pollution data for four criteria air pollutants were extracted from AirNow. Changes in encounter characteristics, viral testing patterns, and air pollution before and after Mar 17, 2020, the date public health interventions to limit viral transmission were enacted in Philadelphia, were assessed and compared to data from 2015-2019 as a historical reference.</p>

<p><strong>RESULTS: </strong>After Mar 17, 2020, in-person asthma encounters decreased by 87% (outpatient) and 84% (emergency + inpatient). Video telemedicine, which was not previously available, became the most highly utilized asthma encounter modality (61% of all visits), and telephone encounters increased by 19%. Concurrently, asthma-related systemic steroid prescriptions and frequency of rhinovirus test positivity decreased, while air pollution levels did not substantially change, compared to historical trends.</p>

<p><strong>CONCLUSION: </strong>The COVID-19 pandemic in Philadelphia was accompanied by changes in pediatric asthma healthcare delivery patterns, including reduced admissions and systemic steroid prescriptions. Reduced rhinovirus infections may have contributed to these patterns.</p>