Is Asthma a Risk Factor for Severe SARS-CoV-2 Pneumonia?

By Scott Baltic

July 20, 2020

NEW YORK (Reuters Health) - Patients with asthma appear not to have an elevated risk for severe SARS-CoV-2 pneumonia, nor does such pneumonia seem to induce severe asthma exacerbation, according to researchers in France.

Asthma is listed as a risk factor for severe COVID-19 illness by the U.S. Centers for Disease Control and Prevention, and other respiratory viral infections are known to be associated with severe asthma exacerbation. A recent study also found COVID-19 patients with asthma had prolonged intubation times. However, early case series have not shown an association between asthma and COVID-19.

"Our results demonstrate that asthmatic patients do not experience differences in clinical symptoms or biological and radiological status in SARS-CoV-2 pneumonia," Dr. Frederic de Blay of Strasbourg University Hospital and colleagues write in The Journal of Allergy and Clinical Immunology: In Practice.

The team reviewed data from a dedicated COVID-19 unit at their hospital, which is also a referral center for asthma patients. In all, 106 patients with SARS-CoV-2 pneumonia were hospitalized there between March 4 and April 6, of whom 23 had asthma.

Pneumonia was diagnosed on the basis of clinical symptoms, chest CT scan and laboratory confirmation of SARS-CoV-2 infection.

About half (52.2%) of the patients with asthma were categorized as Gina 1 and were not receiving inhaled corticosteroids; 39.1% were classed as Gina 4 and 5.

Nearly 20% of patients required admission to the intensive-care unit (ICU) and mechanical ventilation, but the risk of these outcomes did not differ between patients with or without asthma. Nor did asthmatic patients stay longer at the hospital, and none of them died.

"Larger studies would be desirable to confirm our results and understand the mechanisms explaining such findings," the researchers write.

Dr. Daniel Jackson, a specialist in allergy, asthma and immunology at the University of Wisconsin School of Medicine and Public Health in Madison, told Reuters Health by email that while early reports from China and other countries have largely not found asthma to be a risk factor for severe SARS-CoV-2 illnesses, "the mechanisms underlying these observations are not yet clear."

"Patients with asthma are typically at higher risk of severe respiratory illnesses, including both viral and bacterial pneumonia," he said. "It was surprising to many asthma specialists that this does not appear to be true for SARS-CoV-2."

If the reasons for this could be understood, said Dr. Jackson, who was not involved in the new study, "they could provide insight into . . . strategies to prevent or treat COVID-19."

Dr. David M. G. Halpin, a consultant physician and honorary professor of respiratory medicine at the University of Exeter, in the U.K., told Reuters Health that it remains uncertain whether people with asthma truly are at lower risk of COVID-19.

"If a person with asthma develops COVID, they do appear to have a slightly higher risk of more severe disease and death," he said by email.

The reason there are fewer asthmatics among COVID-19 patients than might be expected, he said, could be their shielding behavior, a potential benefit of the therapy they take, or changes in the innate immune system in asthma.

Dr. Halpin, who was not involved in the new study either, concluded, "The key message from the evidence we have so far is that people with asthma should follow all the public health guidance about protecting themselves from infection, like everybody else, and continue taking their medication."

Dr. de Blay did not reply to a request for comment.

SOURCE: The Journal of Allergy and Clinical Immunology: In Practice, online June 27, 2020.


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