Asthma, Severe Acute Respiratory Syndrome Coronavirus-2 and Coronavirus Disease 2019

Dylan T. Timberlake; Kasey Strothman; Mitchell H. Grayson


Curr Opin Allergy Clin Immunol. 2021;21(2):182-187. 

In This Article

Asthma and Coronaviruses

Viral infections are known to cause asthma exacerbations, with HCoV being one of the commonly implicated viruses in asthma exacerbations in adults; in one study, HCoV was isolated in 8.4% of all virus-induced asthma exacerbations.[24] Presumably based on this data, both the Centers for Diseases Control and Prevention and WHO initially listed asthma as a risk factor for severe disease early in the COVID-19 pandemic.[25,26]

Although non-SARS-HCoV has been associated with asthma exacerbations, there is overall a lack of data regarding asthma exacerbations with SARS and MERS. Asthma exacerbations were shown to decrease during the outbreak of SARS in Singapore and Hong Kong.[27] This decrease in asthma exacerbations was most likely related to lifestyle changes, as it was seen in conjunction with a decrease in other common respiratory viral infections; however, the decrease in asthma exacerbations during an epidemic also suggests that SARS itself was not a significant cause of asthma exacerbations. In regard to MERS, a study of 19 MERS patients found an asthma prevalence of 5.3%, which was less than the rate of asthma in uninfected subjects (31%).[28] This study was designed to investigate transmissibility of MERS and did not significantly comment on outcomes. It appears based on these extremely limited data that asthma might be a risk for developing MERS, but any relationship to severity of disease remains unknown. This disparity between outcomes among different viruses within the same family suggests that we must avoid broad generalizations as the risks and outcomes for one HCoV may not apply to other HCoVs (Figure 1).

Dissimilar asthma outcomes with different viruses of the same family have been seen with other respiratory viruses. During nonpandemic influenza seasons, asthma is recurrently found to be a risk factor for hospital admission, intensive care unit (ICU) admission, and severe disease.[29] However, during the H1N1 influenza pandemic in 2009, patients with asthma who were hospitalized with influenza had lower mortality, decreased risk of ICU stay, and decreased need for mechanical ventilation.[30] This discrepancy again demonstrates the fact that asthma risks and outcomes can vary for infections with different viruses of the same family.