People with asthma are classified as being at increased risk for severe COVID-19 outcomes, although evidence is emerging that may point in the opposite direction.
Under normal circumstances, viral infections are a big driver of flares in asthma patients. But research indicates asthma patients with COVID-19 do not appear to have a higher rate of hospitalization or mortality compared with other COVID-19 patients, Linda Rogers, MD, of Icahn School of Medicine at Mount Sinai in New York City, told MedPage Today.
“As we look at data coming out of areas strongly affected by the pandemic, one very striking thing is the lack of high rates of patients with asthma having severe effects” of COVID-19, Rogers said.
For example, she pointed to data from Wuhan, China, indicating that 5% of people in China have asthma yet it was seen in fewer than 1% of patients hospitalized for COVID-19.
Rogers also cited mortality statistics from the New York State Department of Health, in which “asthma is not even in the top 10” comorbidities, even though 8%-10% of New York’s population has asthma. Rogers noted chronic obstructive pulmonary disease (COPD) comes in after hypertension, diabetes, as well as other types of cardiovascular disease, dementia, and renal disease.
This does not necessarily mean asthma is protective, as other factors could explain these lower rates, she added. Patients with asthma may behave differently than patients with other chronic diseases, though Rogers said that seems unlikely, or it could be an artifact of how the data were collected.
But if these can be ruled out, it does at least raise the question of whether asthma or its treatment is “protective,” she said. One reason that may be the case: The presence of type 2 inflammation in asthma or allergies, which is associated with lower expression of ACE2, thought to be the entry receptor for SARS-CoV-2 in host cells.
“That would be a plausible mechanism by which asthma would not be a high-risk condition, and could be a potential link to what we’re observing in the epidemiological data,” Rogers said.
Indeed, she cited evidence pointing to this hypothesis. A study in the Journal of Allergy and Clinical Immunology showed “respiratory allergy and controlled allergen exposures are each associated with significant reductions in ACE2 expression,” and that ACE2 expression was “lowest in individuals with both high levels of allergic sensitization and asthma.”
She also pointed to a commentary in the Lancet Respiratory Medicine suggesting asthma treatments, such as corticosteroids, may play a role. Up to 75% of asthma patients in China use inhaled steroids, which “suppress coronavirus replication and cytokine production” in cultured cells.
“The possibility that inhaled corticosteroids might prevent (at least partly) the development of symptomatic infection or severe presentations of COVID-19 cannot be ignored,” the Lancet Respiratory Medicine authors wrote.
Rogers said steroids may also be associated with lower ACE2 levels, but “many patients are concerned about the effect of inhaled steroids. There are still a lot of unknowns.”
During the COVID-19 outbreak, she advised clinicians to encourage patients with asthma to maintain their asthma control to avoid a flare-up that causes them to be hospitalized.
For more severe patients, Rogers said some anti-interleukin-5 agents for asthma are approved for self-injection at home — i.e., benralizumab (Fasenra) and mepolizumab (Nucala). Anti-IgE therapy for asthma control (omalizumab, Xolair) is not approved for home use, although it comes in a prefilled, single-use syringe. But following a discussion with a provider, “if clinically appropriate, home use may be considered” for patients who are stable, within the setting of COVID-19, Rogers said.
Last Updated May 05, 2020