People with asthma may be at reduced risk of contracting the coronavirus, according to research published last week in the Journal of Allergy and Clinical Immunology.
Israeli researchers tested 37,469 subjects, 6 percent of whom were positive for the virus. Of the subjects positive for the virus, 6.75 percent had asthma, compared to 9.62 percent of those who were negative for COVID-19, according to the study results.
Eugene Merzon, one of the research leaders, told the Jerusalem Post that there were at least three possible explanations, including that asthma is associated with lower levels of angiotensin-converting enzyme 2 (ACE2) receptors, which is a mechanism for the virus to infect cells.
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Merzon, head of the Department of Managed Care in Leumit Health Services, said it was also possible that asthmatics, knowing they are at risk for more severe cases of the virus, may simply take more precautions against contracting it.
The third option he offered is that the inhaled corticosteroids (ICSs) people frequently use to treat asthma may reduce the risk of the virus. He cited studies showing ICSs may cut replication of coronavirus.
Merzon said further study was needed on the matter, noting that the research was based on inpatient data.
“[A]ll these prevalence data were derived from the COVID-19 inpatient population,” the researchers wrote. “Therefore, the prevalence of asthma may be different in outpatient patients with COVID-19.”
Earlier research lends credence to the study results, however. Only 9 percent of patients hospitalized with the virus in New York had asthma, according to prior studies citied by the authors. Patients with asthma also appeared to be less susceptible to previous severe acute respiratory syndromes such as the 2003 SARS epidemic.