Coronavirus SARS-CoV-2 (COVID-19): As of October 2020, there are insufficient data to recommend either for or against specific antiviral or immune-based therapies for patients with mild COVID-19.
About
- COVID-19 is caused by SARS-CoV-2, a novel coronavirus.
Origin
- First identified in Wuhan, China, in late 2019, potentially originating from wet markets where live animals are in close contact with humans.
Aetiology
- SARS-CoV-2 is a coronavirus with four primary structural proteins:
- Spike protein (S): Binds to the angiotensin-converting enzyme 2 (ACE2) receptors on host cells, which are present in the respiratory tract, GI tract, kidneys, brain, and other organs.
- Envelope protein (E): Plays a role in viral assembly and release.
- Matrix protein (M): Stabilizes the virus structure.
- Nucleocapsid protein (N): Protects viral RNA.
- Causes viral pneumonia and has a mortality rate of approximately 1%.
Pathology
- Histopathology shows thickened hyaline membranes, desquamative pneumocytes, mononuclear cell infiltration, and fibroblastic organization in the alveolar spaces.
- ACE2 receptors, which the virus uses for cell entry, are widely expressed beyond the lungs in organs such as the kidneys, liver, and brain.
Groups at Higher Risk
- Elderly populations, nursing home residents, and individuals with co-morbidities (e.g., diabetes, obesity, hypertension, chronic respiratory disease, malignancies, and immunosuppression).
- Ethnic disparities noted with higher risk among Southeast Asian and Afro-Caribbean populations.
- Potential links to low vitamin D levels and immune response are under investigation.
Clinical Features
- Incubation period: 2-14 days, with an average of 5 days.
- Common symptoms include fever, dry cough, dyspnea, fatigue, muscle pain, headache, and confusion.
- Less common symptoms: sore throat, rhinorrhea, chest pain, diarrhoea, nausea, and vomiting.
- Viral pneumonia, often with type 1 respiratory failure (RF), and potential complications include myocarditis and acute kidney injury.
Severity Classification
- Asymptomatic: Positive for SARS-CoV-2 without symptoms.
- Mild Illness: Symptoms like fever and cough, without shortness of breath or abnormal chest imaging.
- Moderate Illness: Evidence of lower respiratory disease with oxygen saturation ≥94% on room air.
- Severe Illness: Signs of respiratory distress, including respiratory rate >30 breaths/min, SpO₂ <94%, PaO₂/FiO₂ <300 mmHg, or lung infiltrates >50%.
- Critical Illness: Includes respiratory failure, septic shock, and/or multiple organ dysfunction.
Complications
- Septic Shock and Cytokine Storm: Characterized by high inflammatory cytokines, leading to deteriorating respiratory and circulatory function. Differential diagnosis should exclude other treatable causes of shock.
- Cardiac Injury: Myocarditis, pericardial dysfunction, and arrhythmias can mimic acute coronary syndromes (ACS).
- Renal and Liver Dysfunction: Significant renal involvement in severe cases, with over 15% requiring continuous renal replacement therapy in critical conditions.
Investigations
- Blood Tests: Common findings include lymphopenia, elevated CRP, raised D-dimer levels, and occasionally elevated liver enzymes.
- Imaging: CXR shows patchy bilateral opacities; CT scan may show ground-glass opacities. CTPA may be indicated to exclude pulmonary embolism.
- Diagnostic Testing: RT-PCR from nasal swabs for viral RNA detection; antibody testing may be performed for immune response.
- Biomarkers: Elevated troponin and BNP levels are possible in cardiac complications.
Prevention
- Social distancing, masks, and hand hygiene.
- Contact tracing and isolation for exposed individuals.
- Environmental Precautions:
- Regular hand hygiene
- Proper PPE usage
- Patient isolation
- Antiseptic use and disinfection
- Safe handling of waste and linen
- Environmental cleaning
- Proper asepsis protocols
Management
- Supportive care, including IV fluids, oxygen, and respiratory support as needed.
- For severe cases requiring respiratory support, consider high-flow nasal cannula or non-invasive ventilation (NIV) with close monitoring for deterioration.
- Mechanical ventilation may be necessary in critical cases, with a preference for low tidal volume strategies and prone positioning to improve oxygenation.
- Pharmacological Interventions: Dexamethasone 6 mg daily for up to 10 days for patients requiring oxygen. Remdesivir remains an experimental treatment.
- Thromboprophylaxis: Routine thromboprophylaxis recommended due to the increased risk of thromboembolic events.