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

Mucosal immunity plays a major role not only in the prevention but probably also in the outcomes of COVID-19. An enhanced production of secretory immunoglobulin A (sIgA) might contribute to the activation of the immune response mechanisms. 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 combined scheme of intranasal and subcutaneous administration of a bacteria-based immunostimulant agent. 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 epithelial, nasal and pharyngeal swabs, and salivary gland secretions at baseline and on days 14 and 30. The combined scheme of intranasal and subcutaneous administration of the Immunovac VP4 vaccine in the complex therapy of patients with COVID-19 is accompanied by increased synthesis of sIgA in nasal and pharyngeal swabs, more intense decrease in the level of C-reactive protein (CRP) and reduction in the duration of fever and length of hospitalization compared to the control group. Prescribing a immunostimulant agent containing bacterial ligands in complex therapy for COVID-19 patients helps to enhance mucosal immunity and improves the course of the disease.

Changes in nasal, pharyngeal and salivary secretory IgA levels in patients with COVID-19 and the possibility of correction of their secretion using combined intranasal and oral administration of a pharmaceutical containing antigens of opportunistic microorganisms.

Background: Although extensive research has been conducted on the role of local immunity in patients with SARS-CoV-2, little is known about the production and concentrations of secretory IgA (SIgA) in different mucosal compartments. This article aims to assess the secretion of SIgA in the nasal and pharyngeal compartments and saliva of patients with COVID-19 and to investigate the possibility and efficiency of correction of their secretion using combined intranasal and oral administration of a pharmaceutical containing antigens of opportunistic microorganisms. Methods: This study included 78 inpatients, aged between 18 and 60 years, who had confirmed COVID-19 with moderate lung involvement. The control group (n=45) received basic therapy, and the treatment group (n=33) was additionally administered the bacteria-based pharmaceutical Immunovac VP4 from day 1 to day 10 of hospitalization. SIgA levels were measured by ELISA at baseline and on days 14 and 30. Results: No systemic or local reactions associated with Immunovac VP4 were reported. We observed a statistically significant reduction in the duration of fever and hospitalization in patients who received Immunovac VP4 compared with those from the control group (p=0.03 and p=0.05, respectively). Changes over time in SIgA levels in nasal swabs were found to be significantly different in the two treatment groups (F=7.9, p[78.0]<0.001). On day 14 of observation, patients in the control group showed a statistically significant reduction in SIgA levels from baseline (p=0.02), whereas patients in the Immunovac VP4 group had stable SIgA levels (p=0.07). On day 30 after the start of treatment, there was a statistically significant increase in SIgA levels in the Immunovac VP4 group compared with baseline (from 77.7 (40.5-98.7) µg/L to 113.4 (39.8-156.7) µg/L; p=0.05) and the levels measured on day 14 (from 60.2 (23.3-102.9) µg/L to 113.4 (39.8-156.7) µg/L; p=0.03). The control group showed a statistically significant decrease in levels of nasal SIgA (to 37.3) on day 30 (p=0.007 for comparison with baseline values and p=0.04 for comparison with levels measured on day 14). Changes over time in SIgA levels measured in pharyngeal swabs were also different between the two treatment groups, and this difference reached statistical significance (F=6.5, p[73.0]=0.003). In the control group, this parameter did not change throughout the study (p=0.17 for a comparison between the levels measured on day 14 and the baseline values, and p=0.12 for a comparison between the levels measured on day 30 and the baseline values). In the Immunovac VP4 group, there was a statistically significant increase from baseline in SIgA levels on study day 30: from 1.5 (0.2-16.5) µg/L to 29.8 (3.6-106.8) µg/L (p=0.02). Changes over time in salivary SIgA did not show a significant difference between study groups (F=0.3, p[66.3]=0.75). Conclusion: As part of combination therapy, the bacteria-based immunostimulant agent Immunovac VP4 increases SIgA levels in the nasal and pharyngeal compartments and induces clinical improvement. Induced mucosal immunity is central to the prevention of respiratory infections, particularly in patients with post-COVID-19 syndrome.