`Secretory IgA and course of COVID-19 in patients receiving a bacteria-based immunostimulant agent in addition to background therapy

Abstract

Abstract Scientific Relevance: Mucosal immunity plays a major role not only in the prevention but probably also in the outcome of COVID-19. An enhanced production of secretory immunoglobulin A (sIgA) might contribute to the activation of the immune response mechanisms. Study Objective: To assess the levels of sIgA produced by epithelial cells in the nasal and pharyngeal mucosa and those measured in salivary gland secretions and to study the course of COVID-19 following the intranasal or subcutaneous administration of a bacteria-based immunostimulant agent. Materials and Methods: This study included 69 patients, aged between 18 and 60, who had moderate COVID-19 infection. They were divided into two groups: Group 1 (control group) included 39 patients who received only background therapy, and Group 2 was made up of 30 patients who received background therapy in combination with the Immunovac VP4 vaccine, a bacteria-based immunostimulant agent, which was given for 11 days starting from the day of admission to hospital. The levels of sIgA were measured by ELISA in nasal epithelial swabs, pharyngeal swabs, and salivary gland secretions at baseline and on days 14 and 30. Results: The convalescence phase of moderate COVID-19 was associated with a decrease in sIgA levels in nasal swabs, persistently high sIgA levels in salivary gland secretions, and no changes in pharyngeal swabs with the levels similar to those in healthy subjects. The addition of an immunostimulant agent to combination therapy for patients with COVID-19 stimulates the production of sIgA in the nasal and pharyngeal compartments, reduces C-reactive protein (CRP) levels and shortens the duration of fever and the length of hospital stay. Conclusion: Using an immunomodulatory agent containing bacterial ligands in therapy for COVID-19 patients enhances the production of sIgA in the nasal and pharyngeal compartments and improves the course of the disease.