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Asthma patients with confirmed COVID-19 were no more likely to require hospitalization or mechanical ventilation than patients without asthma, researchers found.

Moreover, the asthma patients were less likely to die from COVID, reported Lacey Robinson, MD, of Massachusetts General Hospital in Boston, at the virtual annual meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI).

In a matched cohort analysis, 21% of asthma patients with COVID-19 were hospitalized compared with 18% of patients without asthma, and their mortality rates were 1% and 3%, respectively.

The study is the latest to suggest that asthma patients as a group are at no greater risk from SARS-CoV-2 infection than the general population, and that they may even have extra protection against developing severe disease.

These findings and those from other recent studies should reassure asthma patients, Robinson said.

"What we showed and what others have shown is that asthma alone really isn't a risk factor for severe outcomes from COVID-19, and that is great news for asthma patients," she told MedPage Today.

Robinson noted that the asthma cohort in the study did not include patients with chronic obstructive pulmonary disease (COPD) or other respiratory diseases that have been linked to worse outcomes with COVID, but they did have more comorbidities and higher body mass indexes, on average, than patients without asthma.

The study included data from Mass General, Brigham and Women's Hospital, and affiliated Boston-area hospitals on patients with COVID-19 confirmed from early March to early June 2020. They did not have COPD, cystic fibrosis, or interstitial lung disease.

Asthma was defined as two or more asthma diagnosis codes and asthma medication prescription in the year prior to COVID-19 diagnosis. Patients serving as controls were matched for age within 5 years, sex, and date of positive test within 7 days, and primary outcomes included hospitalization, mechanical ventilation, and death. Patients were followed for these outcomes until July 2, 2020. Totals of 562 asthma patients and 2,686 matched comparators were included.

Adjusted hazard ratios among asthma patients were 0.99 (95% CI 0.80-1.22) for hospitalization, 0.69 (95% CI 0.36-1.29) for mechanical ventilation, and 0.30 (95% CI 0.11-0.80) for death.

A separate systematic review and meta-analysis presented at the AAAAI meeting also indicated that asthma didn't worsen outcomes in COVID-19.

Researchers from the Mayo Clinic in Rochester, Minnesota, examined 17 retrospective studies and one prospective cohort study published through early October 2020. Two of the studies specifically evaluated outcomes among pregnant patients and two included only pediatric patients.

Among patients with COVID-19, having asthma was not associated with significantly increased risks of hospitalization (OR 1.46, 95% CI 0.29-7.28), length of hospitalization (OR 1.59, 95% CI -0.55 to 3.74), ICU admission (OR 1.65, 95% CI 0.56- 4.17), or death (OR 0.73, 95% CI 0.38-1.40).

Mayo's Andrea Sitek, MD, said the meta-analysis showed a trend toward lower risk of death among patients with asthma, but also a nonsignificant trend toward increased hospital admission, ICU admission, and hospital length of stay.

She acknowledged that the necessary reliance on observational data, along with the significant heterogeneity among the studies for each of the assessed outcomes, were study limitations.

Researchers have speculated on the mechanisms that might explain a possible protective effect for asthma against progression to severe COVID-19.

It has been suggested that decreased angiotensin-converting enzyme (ACE) 2 expression may reduce the risks of severe disease and death, or that Th2 cytokines in patients with asthma may promote protective immunity.

Use of inhaled corticosteroids, such as budesonide or ciclesonide, by patients with asthma may also reduce the risk of infection or severe COVID-19 disease.

"These are all just theories, but I believe we will learn more about this soon," Robinson told MedPage Today.

"It is very important that we understand it, because it could help us also understand more about this virus and the pathogenesis of severe disease. If [asthma] patients are doing better, maybe that is a key for helping to prevent other patients from getting very sick," she added.