During the early days of the COVID-19 pandemic, curtailed healthcare services combined with patients reluctance to make in-person visits to healthcare providers resulted in significant disruptions in patient care, with patients delaying or foregoing care.  Among the shifts in utilization seen during the pandemic was a sharp drop in asthma exacerbations (up to 90% in a pediatric population, for example), prompting concerns that patients were not receiving needed care.1

However, findings of multiple studies suggest that patients with asthma likely did not forego needed care – because asthma exacerbations actually decreased during the early days of the COVID-19 pandemic.1-6 One such study, the PREPARE trial (Patient Empowered Strategy to Reduce Asthma Morbidity in Highly Impacted Populations – PeRson EmPowered Asthma RElief; ClinicalTrials.gov Identifier: NCT02995733), investigated changes in asthma exacerbation rates among African American and Hispanic/Latinx adults (n = 1178) from 19 clinical practices across the US. The PREPARE study analyzed monthly patient self-reports, collected from November 2018 through March 2020, using the Asthma Exacerbation Questionnaire.2,3

In an article published in the July 2021 Journal of Allergy and Clinical Immunology: In Practice, PREPARE investigators reported a 41% relative reduction in asthma exacerbations during the first and second quarters of 2020 vs those same quarters during previous years of the study.2 Notably, greater reductions were observed in Hispanic/Latinx patients (50%) compared to African American/Black patients (27%) and in individuals who worked outside of the home (65%) before the pandemic compared to those working at home (23%).2

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“For Black/African-American and Hispanic/Latinx individuals with moderately severe asthma, there was nearly a halving of asthma exacerbations following the coronavirus disease 2019 (COVID-19) pandemic, a decrease most significant for individuals working outside of the home and in those without type 2 inflammation, suggesting environmental or common viral triggers for asthma exacerbations,” PREPARE investigators noted.2

Overall, study participants with non-type 2 inflammation showed greater improvement than those without this phenotype, with reductions of 51% vs 34% in those with low vs high blood eosinophil counts, and a 45% reduction vs a 4% increase in those with low vs high fractional excretion of nitric oxide (FeNO).2 These results remained unchanged after controlling for changes in air quality factors including particulate matter 2.5 (P =.005), nitrogen dioxide (P =.017), and ozone (P =.0028).2

Supporting the PREPARE study, international studies from England, Hong Kong, Scotland, and Wales have also reported decreased asthma exacerbations during the pandemic. 4-6 For example, a study in Hong Kong found admissions for asthma exacerbations significantly decreased by 53.2% (95% CI, 50.4–55.8%) in 2020 compared with monthly average admissions in 2015 through 2019, and that exacerbations decreased by 0.8% with every 1% increase in masking (95% CI, 0.8–0.9%).5 Likewise, analyses of utilization data from Scotland and Wales found a 36% pooled reduction in emergency asthma admissions (incidence rate ratio [IRR], 0.64; 95% CI, 0.49-0.83; P =.001) during COVID-19 lockdown, with no significant change in asthma-related deaths (pooled IRR, 0.57; 95% CI, 0.17-1.94; P =.37).6

Additionally, a US study of asthma exacerbations in a pediatric population (n = 3959), published in July 2021 in Pediatric Pulmonology, showed that exacerbations decreased by 75% during the first 12 months of the pandemic compared to the previous 12 months.1 In this study, which used electronic health records data, exacerbations were “defined as encounter type with an asthma diagnosis code (J45.x) and the administration or prescription for an oral corticosteroid.” According to the authors, these findings indicate that measures implemented in response to COVID-19 may have led to improved outcomes in children with asthma.

To examine the broader implications of decreased asthma exacerbations during the COVID-19 pandemic, Pulmonology Advisor interviewed Justin D. Salciccioli, MD, fellow in pulmonary and critical care medicine at Brigham and Women’s Hospital of Harvard Medical School in Boston and lead author of the PREPARE study.

What are believed to be the reasons why reductions in asthma exacerbations during COVID-19 were observed in your study? 

A number of potential explanations may account for this finding. With pandemic response measures such as mask-wearing, social distancing, and working from home, this decrease in exacerbations could be due to reduced exposures to common viral respiratory infections or other environmental triggers for asthma.

Were you and your colleagues surprised by your findings? 

Asthma management has recently focused on treating individuals with high levels of eosinophilic inflammation with targeted biologic therapies. However, we found that the reduction in asthma exacerbations after the pandemic were greatest in individuals without the eosinophilic inflammatory type.

This was a surprising result but biologically plausible given that the likely triggers for asthmatics with non-eosinophilic inflammation are typically environmental. This was an important result because the magnitude of the reduction in exacerbations in these patients was about as great as, if not greater than, the effect of biologic therapies for asthma patients with eosinophilic inflammation.

What are the implications of these observations for clinicians? 

We are still trying to figure out whether the measures that were employed to slow the spread of COVID-19 may also help to improve asthma control in these high-risk patients. Although we do not currently have this data, we may find that some individuals with asthma may benefit from wearing face coverings to prevent common viral pathogen exposures.

What additional research questions do these findings evoke?  

These data are important in highlighting that the measures used to prevent the spread of COVID-19, such as mask-wearing, social distancing, hand-washing, and working from home may all help to reduce the burden of asthma in individuals with difficult-to-control asthma.

Future research should attempt to identify patient attitudes toward non-pharmacologic interventions and to attempt to quantify the individual effect of each of these interventions on asthma control.

Most importantly, while patients with noneosinophilic asthma have had few options for improved control, these data highlight potential areas for therapeutic improvement and improved control in this sub-group of patients.


1. Hurst JH, Zhao C, Fitzpatrick NS, Goldstein BA, Lang JE. Reduced pediatric urgent asthma utilization and exacerbations during the COVID-19 pandemic. Published online July 21, 2021. Pediatr Pulmonol. doi:10.1002/ppul.25578

2. Salciccioli JD, She L, Tulchinsky A, Rockhold F, Cardet JC, Israel E. Effect of COVID-19 on asthma exacerbation. J Allergy Clin Immunol Pract. 2021;9(7):2896-2899.e1. doi:10.1016/j.jaip.2021.04.038

3. Israel E, Cardet JC, Carroll JK, et al. A randomized, open-label, pragmatic study to assess reliever-triggered inhaled corticosteroid in African American/Black and Hispanic/Latinx adults with asthma: design and methods of the PREPARE trial. Contemp Clin Trials. 2021;101:106246. doi:10.1016/j.cct.2020.106246

4. Shah SA, Quint JK, Nwaru BI, Sheikh A. Impact of COVID-19 national lockdown on asthma exacerbations: interrupted time-series analysis of English primary care data. Thorax. 2021;76(9):860-866. doi:10.1136/thoraxjnl-2020-216512

5. Chan KF, Kwok WC, Ma TF, et al. Territory-wide study on hospital admissions for asthma exacerbations in the COVID-19 pandemic. Ann Am Thorac Soc. 2021;18(10):1624-1633. doi:10.1513/AnnalsATS.202010-1247OC6.

6. Davies GA, Alsallakh MA, Sivakumaran S, et al. Impact of COVID-19 lockdown on emergency asthma admissions and deaths: national interrupted time series analyses for Scotland and Wales. Thorax. 2021;76(9):867-873. doi:10.1136/thoraxjnl-2020-216380