Post-COVID Respiratory Sequelae in COPD: Mucus Plugging, Infectious Complications, and Risk-Stratified Follow-Up

Context/Objectives: In patients with COPD (chronic obstructive pulmonary disease), SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection represents an overlap of viral injury on a lung already affected by pathological mucus, altered mucociliary clearance, chronic inflammation, and impaired antiviral immunity. Methods: A focused narrative review (2020-2025) was conducted using clinical, experimental, and consensus evidence. The evidence was synthesized qualitatively, with priority given to cohort studies, meta-analyses, and mechanism-focused studies with clinical relevance. Results: Mucus obstruction ("mucus plugs") is frequent in COPD (41-67%) and is associated with unfavorable outcomes. COPD also increases the risk of post-COVID respiratory sequelae. Bacterial coinfection at presentation is uncommon (3-5%), whereas secondary bacterial infections are more frequent (14-18%), especially in severe disease requiring intensive care, where VA-LRTI/VAP (ventilator-associated lower respiratory tract infection/ventilator-associated pneumonia) become predominant. Sepsis, whether viral or mixed, reflects disease severity and may contribute to functional decline and susceptibility to reinfections; however, the concept of a post-acute "sepsis legacy" in COPD after COVID-19 should currently be regarded as a clinically plausible but still emerging hypothesis rather than an established COPD-specific outcome. During recovery, acute exacerbation risk rises to 5.6% versus 3.9%, peaking in the first 30 days after severe disease (aHR ≈ 8.14). Persistent dyspnea and reduced DLCO (diffusing capacity for carbon monoxide) suggest ARDS-related injury, tissue remodeling, and microvascular dysfunction. Conclusions: In COPD, post-COVID respiratory sequelae result from the interaction of mucus, immunity, and infectious/sepsis-related complications. The first post-discharge month is a critical period requiring careful risk stratification and targeted follow-up.