Airway and Systemic Immune Responses Following the Third COVID-19 Vaccination in COPD Patients

Introduction: Booster vaccinations are required to maintain protection against COVID-19. COPD patients are at higher risk of developing severe illness following SARS-CoV-2 infection. Previous cross-sectional analysis after the second COVID-19 booster showed similar immune responses in COPD patients and controls, but pre-vaccination samples were not available. This longitudinal study evaluated systemic and airway immune responses in COPD patients using samples obtained pre- and post-third COVID-19 vaccination. Methods: Twelve COPD patients were recruited, with plasma, nasal and sputum (n = 10) samples collected pre-vaccination and 4- and 14-weeks post vaccination. Samples were analyzed for anti-spike IgA and IgG and cellular immunity. The ability of plasma and nasal samples to block ACE2-spike protein interaction was assessed for Wild type, Delta, and Omicron spike variants. Results: Vaccinations increased anti-spike IgG in plasma (p < 0.001), nasal (IgG p < 0.001) and sputum (p = 0.002) samples, IgA in plasma (p < 0.001) and blood cellular immunity (p = 0.001). Plasma and nasal anti-spike IgA levels correlated (rho: 0.6, p = 0.02), with similar results for IgG (rho: 0.79, p = 0.003). Post-vaccination nasal (p = 0.002) and plasma (p < 0.001) samples were less effective at blocking Omicron spike binding to ACE2 compared to the Wild type spike variant. Discussion: Airway and systemic immune responses against SARS-CoV-2 increased in COPD patients following a third COVID-19 vaccination. Nasal and systemic responses in COPD patients were less effective against Omicron variant compared to previous variants.