Is Asthma a Risk Factor for Coronavirus Disease-2019 Worse Outcomes?

The Answer Is No, But...

Priscila A. Franco; Sergio Jezler; Alvaro A. Cruz


Curr Opin Allergy Clin Immunol. 2021;21(3):223-228. 

In This Article

Is Asthma More Often Associated With Severe Coronavirus Disease-2019?

Viral infections are the most frequent causes of exacerbations in patients with chronic respiratory diseases. Considering the high prevalence of asthma and the astonishing spread and exponentially increasing incidence of COVID-19, and the potential harm respiratory viruses may produce to patients with asthma, there were reasons for major concerns at the beginning of the pandemic. But so far, asthma has not been consistently identified as a frequent comorbidity associated with COVID-19 hospitalizations or deaths. A report by leaders of the WHO Global Alliance against Chronic Respiratory Diseases,[6] highlights the varied frequencies of comorbid asthma observed in COVID-19 patients. In Wuhan it was 0.9%,[7] whereas a higher frequency of 9% was reported among the US COVID-19 patients.[8] In the UK, the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) reported 14,5% of hospitalized COVID-19 patients have asthma.[9] In the State of Sao Paulo, Brazil, according to reports of the Health Department, the frequency of asthma among 42 788 individuals who died with COVID-19 in 2020 was 3.1%, much lower than the reported prevalence of asthma in the Country. It was also 10 times less frequent than diabetes, observed in 43.3%.[10]

People with asthma are not at increased risk of acquiring COVID-19. A systematic review did not show an increased risk of COVID-19 in people with asthma.[11] Handwashing, masks and social/physical distancing have reduced the incidence of other respiratory infections in 2020. As a result, many countries are seeing a reduction in asthma and COPD exacerbations. An analysis of the databases of the Public Health System of Brazil[12] performed for the purpose of this publication, comparing hospital admissions because of asthma from April to September 2019 to the same period of 2020, which represents the peak of the first wave of the epidemic, indicates the admissions because of asthma have been markedly reduced to less than a half in the entire Country and in each of its five geographic regions, as presented in Figure 1. These unexpected and remarkable reductions in hospital admissions may be attributable to some protection provided by atopy,[13] by protection related to the use of inhaled corticosteroids,[14] or else by better adherence to treatment and preventive measures, and finally to fear of attending any heath service or unavailability of beds. Therefore, the reduction in hospitalizations may not necessarily reflect a proportional reduction in morbidity but certainly argue against a higher risk of SARS-CoV-19 infection, worse outcomes of COVID-19 or deterioration of asthma control and exacerbations being associated with COVID-19 in patients with asthma.

Figure 1.

Hospital admissions because of asthma in the Public Health System in Brazil. A comparison of two periods: April to September 2019 (no COVID-19) and April to September 2020 (peak of the first wave of COVID-19). COVID-19, coronavirus disease-2019.