Bacterial lysates in modifying sIgA levels in the upper respiratory tract in COVID-19 patients.

A great deal of evidence has accumulated suggesting an important role of mucosal immunity not only in preventing COVID-19 but also in the pathogenesis of this infection. The aim of the study was to evaluate the levels of secretory immunoglobulin A (sIgA) in different compartments of the upper respiratory tract in COVID-19 patients in relation to the severity of the disease and treatment with a bacteria-based immunomodulating agent (Immunovac VP4). The titers of sIgA were determined by ELISA in nasal epithelial swabs, pharyngeal swabs, and salivary gland secretions at baseline and on days 14 and 30 of treatment.