COVID-19

Symptoms

• Variable — fever, cough, dyspnea, fatigue, myalgia, headache, sore throat, rhinorrhea, congestion
• GI: nausea, vomiting, diarrhea, anorexia
• Anosmia/ageusia (more common with earlier variants)
• Severe disease (typically week 2): worsening dyspnea, hypoxia, respiratory failure, ARDS
• Pediatric: usually mild; MIS-C (multisystem inflammatory syndrome) ~4-6 weeks post-infection — fever, rash, conjunctivitis, GI symptoms, shock (Kawasaki-like)
• Long COVID: persistent fatigue, dyspnea, cognitive impairment ('brain fog'), POTS, post-exertional malaise, anosmia >12 weeks

Signs / physical exam

• Fever, tachypnea, hypoxia (sometimes 'silent hypoxia' — low SpO2 without distress)
• Bilateral crackles, sometimes wheezing
• Often unremarkable exam in mild disease

Classic findings

Patient with new dyspnea, hypoxia disproportionate to chest exam, and bilateral peripheral/lower-lobe ground-glass opacities on CT — consider COVID-19. Silent hypoxia (SpO2 <90% with patient comfortable) is a clue.

Diagnostic criteria

Positive SARS-CoV-2 RT-PCR or antigen test in symptomatic patient or exposed contact.

Labs

• SARS-CoV-2 RT-PCR (gold standard) or rapid antigen test (good for symptomatic, less sensitive in pre-symptomatic phase)
• CBC (lymphopenia common), CMP, LDH, ferritin, D-dimer, CRP, procalcitonin (low in pure viral; may help guide antibiotic decisions), troponin if cardiac symptoms
• ABG if hypoxic; consider blood cultures if concern for bacterial superinfection
• Coagulation studies in severe disease (DVT/PE risk increased)

Imaging

• Chest X-ray — bilateral patchy or peripheral infiltrates
• CT chest (if needed) — peripheral ground-glass opacities, often bilateral and lower lobe; 'crazy paving' in severe disease
• Echocardiography if myocarditis suspected or hemodynamic compromise

First-line

• Outpatient, high-risk for progression (within 5-7 days of symptom onset):
• • Nirmatrelvir-ritonavir (Paxlovid) 300/100 mg PO BID × 5 days — first-line; many drug interactions via CYP3A4; renal dose adjust
• • Remdesivir 200 mg IV day 1, then 100 mg IV daily × 2 more days (outpatient infusion) — alternative when Paxlovid contraindicated
• • Molnupiravir 800 mg PO BID × 5 days — third-line; modest efficacy; contraindicated in pregnancy
• Hospitalized, requiring supplemental oxygen:
• • Remdesivir × 5 days
• • Dexamethasone 6 mg PO/IV daily × up to 10 days (RECOVERY trial — mortality benefit if oxygen required)
• • Add immunomodulator if progressing (high oxygen need or ICU): tocilizumab (anti-IL-6) or baricitinib (JAK inhibitor)
• Anticoagulation: prophylactic dose enoxaparin for hospitalized non-ICU patients; therapeutic dose in select non-ICU patients per ACTIV-4a; prophylactic dose in ICU
• Lung-protective ventilation (TV 6 mL/kg IBW), prone positioning for ARDS

Second-line / adjunct

• Convalescent plasma generally not recommended (limited efficacy in most settings)
• Monoclonal antibodies — variable activity by variant; many de-authorized due to emerging resistance
• Tixagevimab-cilgavimab (Evusheld) — pre-exposure prophylaxis (de-authorized 2023 due to variant resistance)
• Updated mRNA vaccines (Pfizer-BioNTech, Moderna) and protein-subunit vaccine (Novavax) — primary prevention; recommendations updated periodically
• Long COVID: symptom-targeted multidisciplinary care; pulmonary rehab, cognitive rehab, autonomic management