Updated October 2025

Pulmonology | Post-acute Sequelae of SARS-CoV-2

Long COVID and Post-infectious Pulmonary Syndromes

Long COVID frequently involves persistent respiratory symptoms with variable objective impairment. Dominant pulmonary phenotypes include dyspnea with normal imaging/PFTs, small-airway disease with air-trapping, post-viral organizing pneumonia, pulmonary vascular disease/PE, and post-COVID interstitial lung disease with fibrotic change. Evidence supports structured evaluation (symptom assessment, pulse oximetry, PFTs with DLCO, 6MWT, chest CT when indicated) and targeted management including pulmonary rehabilitation, cautious steroid trials for organizing pneumonia, and standard evidence-based care for PE. True progressive post-COVID pulmonary fibrosis appears uncommon but clinically significant in selected survivors of severe pneumonia/ARDS.

Clinical question

What are the prevalent pulmonary phenotypes of Long COVID, how common are they, and what evaluation and management pathways are supported by current evidence?

Long COVIDDyspneaPulmonary FibrosisOrganizing PneumoniaPulmonary EmbolismSmall-Airway DiseaseRehabilitation

Key points

Recognize heterogeneous respiratory phenotypes

Long COVID presents with dyspnea, cough, chest pain, and exercise intolerance, often with discordance between symptoms and routine tests. Distinguish small-airway disease, organizing pneumonia, post-PE dyspnea, and fibrotic ILD to guide therapy ^[1], ^[7], ^[11], ^[12].

Structured evaluation is essential

Prioritize symptom scores, oximetry at rest and exertion, PFTs with DLCO, 6MWT, and targeted chest CT for persistent symptoms or abnormal tests. Screen for PE when indicated; many abnormalities track with acute severity ^[4], ^[11], ^[12].

Rehab improves function across phenotypes

Pulmonary rehabilitation and graded, symptom-titrated activity demonstrate clinically meaningful gains in ILD and post-COVID cohorts; integrate breathing retraining and pacing strategies ^[8].

Inflammation vs. fibrosis dictates therapy

Suspected organizing pneumonia may respond to corticosteroids, whereas established fibrosis requires supportive care and ILD-directed management; antifibrotics remain investigational in post-COVID fibrosis ^[8], ^[12].

Do not miss vascular complications

Pulmonary embolism and chronic thromboembolic disease contribute to persistent dyspnea; follow standard diagnostic and anticoagulation pathways ^[5], ^[12].

Evidence highlights

≈10–35% across studies ^[1], ^[7]

Global long COVID prevalence after infection

Shortness of breath 27%–30% in surveys ^[2], with cough ≈33% in clinic cohorts ^[3]

Common respiratory complaints

Post-COVID pulmonary fibrosis in a subset of severe cases ^[6], ^[8], ^[10]

Most impactful long-term pulmonary morbidity

Phenotypes

Pulmonary Manifestations of Long COVID

Clinically relevant syndromes span airway, interstitial, and vascular compartments with variable imaging and physiological correlates.

Dyspnea with normal spirometry and imaging

Common and multifactorial: deconditioning, dysfunctional breathing, microvascular dysregulation, or autonomic features. DLCO may be mildly reduced even when spirometry is normal ^[1], ^[11].

Small-airway disease and air-trapping

Patients report exertional dyspnea and cough; expiratory CT may reveal air-trapping despite normal inspiratory CT and spirometry. Severity correlates with acute illness severity ^[4], ^[11].

Organizing pneumonia (post-viral inflammatory ILD)

Persistent ground-glass opacities and perilobular consolidations with subacute dyspnea and cough. Many improve spontaneously; a subset respond to a cautious corticosteroid taper when clinically significant ^[8], ^[12].

Post-COVID interstitial lung disease with fibrotic change

Fibrotic bands, traction, and architectural distortion after severe pneumonia/ARDS. True progressive fibrosis is less common but accounts for significant morbidity; risk scales with acute disease severity ^[6], ^[8], ^[10].

Pulmonary vascular disease

Acute/subacute pulmonary embolism and sequelae (including chronic thromboembolic disease) present with chest pain, dyspnea, and exercise limitation; maintain a low threshold for imaging in high-risk patients ^[5], ^[12].

Delayed inflammatory pulmonary syndrome

A life-threatening hyperinflammatory condition in the subacute phase (around week 4) with hypoxemia and radiographic progression, requiring prompt recognition and immunomodulatory care ^[9].

Path to Diagnosis

Evaluation Algorithm

Begin broadly, then tailor testing to phenotype and severity.

Initial Assessment

Symptom inventory: dyspnea, cough, chest pain, exercise intolerance, orthopnea ^[1], ^[7]

Vitals and pulse oximetry at rest and with exertion (1-min sit-to-stand or 6MWT) ^[11]

Baseline labs as indicated (CBC, BMP); consider D-dimer if PE risk features present ^[12]

Physiology

Full PFTs with DLCO; DLCO reduction is common and prognostically informative ^[11], ^[12]

6MWT with desaturation monitoring; consider CPET for unexplained dyspnea after basic workup ^[1], ^[11]

Imaging Strategy

Chest radiograph if symptoms persist >4–6 weeks post-acute illness ^[11]

Low-dose inspiratory chest CT for abnormal exam, persistent hypoxemia, or impaired PFTs; add expiratory CT if small-airway disease suspected ^[4], ^[12]

CT pulmonary angiography when clinical probability of PE is intermediate/high ^[5], ^[12]

Red Flags

Rest/exertional hypoxemia, pleuritic chest pain, hemoptysis, syncope, rapidly progressive dyspnea ^[5], ^[9], ^[12]

Phenotype-Directed Treatment

Organizing pneumonia: consider a monitored prednisone taper when clinically significant; reassess with symptoms and PFTs ^[8], ^[12]

Suspected fibrosis: supportive care, optimize comorbidities; antifibrotics remain investigational post-COVID ^[8], ^[10]

Small-airway disease: trial inhaled bronchodilator ± inhaled corticosteroid case-by-case; incorporate breathing retraining ^[1], ^[11]

Pulmonary embolism: standard anticoagulation per guidelines; evaluate for chronic thromboembolic disease if persistent dyspnea ^[5], ^[12]

Follow-up and Recovery

Repeat PFTs and functional testing at 8–12 weeks and every 3–6 months if impaired ^[11]

Re-image only if symptoms or physiology worsen or fail to improve ^[12]

Enroll in pulmonary rehabilitation to improve dyspnea, endurance, and quality of life ^[8]