Eosinophil Levels in Blood of COVID-19 Patient’s VS Seasonal Allergy

Abstract

Eosinophilia, a peripheral blood with eosinophil count of more than 450 cells per microliter has been linked to allergies, medication responses, among others. However, the reduction in eosinophil levels has been particularly found to be having linkage with SARS-CoV-2 infection. This study aims at comparing COVID-19 patients' peripheral blood eosinophil levels to seasonal allergy patients' eosinophil counts to determine whether there is a link between eosinophil numbers and COVID-19 disease severity. Data was obtained from the review of the electronic medical records of 300 confirmed COVID-19 patients, alongside their clinical features were obtained. Data collected was then subjected to retrospective cohort analysis. Eosinopenia was found in 73.7 percent, 86.7 percent, and 94.3 percent of patients in the mild, moderate, and severe categories, respectively (p value 0.002). When compared to patients with moderate and severe illnesses, patients with critical disease had significantly lower eosinophil levels. Results from this study shows that increase in COVID-19 severity is associated with a significant drop in peripheral eosinophil levels, and that eosinopenia was present in the majority of COVID-19 patients. Seasonal allergic rhinitis is indicated as a particularly good model for studying the potential pathogenic effects of eosinophils and eosinophilic inflammation.