Denisa E. Ferastraoaru, M.D., Manish Ramesh, M.B.B.S., Ph.D., and colleagues retrospectively studied nearly 1,000 asthma patients who were seen at Montefiore Medical Center’s emergency department (ED) due to COVID-19. The researchers found that asthmatics seen in the ED who had preexisting eosinophilia (elevated levels of white blood cells known as eosinophils) were significantly less likely to require hospital admission for COVID-19 compared with other asthma patients.

Overall, 85% of asthma patients admitted to the hospital had eosinopenia (no detectable eosinophils). Those hospitalized asthma patients whose eosinophil count rose above 150 cells/microliter during hospitalization were significantly less likely to die compared with admitted asthma patients whose eosinophil count remained below 150 cells/microliter during admission. Eosinophilia is a characteristic of a type of asthma known as eosinophilic,Th2-high or allergic asthma.

The findings suggest that patients with allergic asthma may be less severely affected by COVID-19 compared with people with other types of asthma. In addition, monitoring asthmatics’ eosinophil levels could help to indicate whether asthmatics hospitalized with severe COVID-19 are improving or not.

The study was published online on January 22 in the Journal of Allergy and Clinical Immunology: In practice, Dr. Ferastraoaru is an assistant professor of medicine at Einstein and an attending physician at Montefiore. Dr. Ramesh is an assistant professor of medicine at Einstein.