Evaluation of Salivary sIgA Levels in Hospitalized COVID-19 Patients with COVID-19 Disease Severity: A Cross-sectional Study

Since late 2019, the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) pandemic has dramatically affected public health worldwide. Although systemic antibodies like Immunoglobulin G (IgG) and Immunoglobulin M (IgM)have been widely studied in Coronavirus disease 2019 (COVID-19), the role of Immunoglobulin A (IgA) in mucosal immunity remains less understood. This study evaluated whether salivary IgA levels could serve as prognostic markers for disease severity, progression, and outcomes in hospitalized patients with COVID-19. In this cross-sectional study, 61 hospitalized patients with COVID-19 were enrolled. After obtaining informed consent, saliva samples were collected at admission to measure IgA levels using an ELISA-based assay. Comprehensive clinical and laboratory data, including chest CT results, oxygen saturation, inflammatory markers, and clinical outcomes, were also recorded. Statistical tests were used to examine the association between salivary IgA levels and disease severity, progression, and outcomes. We enrolled 61 hospitalized patients with COVID-19 (30 females, 31 males; mean age: 56.20 ± 17.45 years; mean admission oxygen saturation: 89.98 ± 5.77%). At admission, 39.3% of patients reported dyspnea, and 40% demonstrated severe lung involvement on chest CT scans. The mean salivary IgA level was 1729.69 ± 391.35 mg/dL. No significant associations were found between salivary IgA levels and COVID-19 severity, disease progression, or clinical outcomes, including mortality. Our findings show that salivary IgA levels did not significantly correlate with COVID-19 severity, disease progression, or clinical outcomes in hospitalized patients. Therefore, salivary IgA alone cannot be recommended as a prognostic biomarker for COVID-19. Further research is needed to identify more reliable immunological indicators for predicting COVID-19 severity and outcomes.