Some COVID-19 patients present with eosinophilic inflammation. Is it a Th2-driven response against the virus or an innate immune response?
Eosinopenia has been reported in ⁓50-70% of severe COVID-19 patients. A minority of COVID-19 patients present with eosinophilic inflammation.22,49 The Th1/Th2 cytokine balance may play a role, particularly as it pertains to IL-5, which promotes eosinophilopoiesis and eosinophil survival and activation. Eosinophilic inflammation suggests the dominance of type 2 inflammation, which may play a protective role against SARS-CoV-2. On the other hand, it may be the result of a hypersensitivity reaction to drugs used to treat COVID-19.50-52