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COVID-19
COVID-19

COVID-19

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🏘 Epidemiology

COVID-19 falls under a family of ssRNA viruses called coronaviruses. They are called this due to their crown-like appearance on electron microscopy. 3 coronaviruses have caused pandemics thus far:

  1. Severe Acute Respiratory Syndrome (SARS)
  2. Middle Eastern Respiratory Syndrome (MERS)
  3. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) aka COVID-19

It was first identified in December 2019 in Wuhan, China. It has since caused a pandemic that has resulted in >536 million cases and >6.3 million deaths worldwide. It is estimated that approximately 45% of the world population has been infected at once.

It is transmitted via respiratory droplets. Fomite transmission (transmission via objects) may also occur.

Pathophysiology

The exact pathophysiology is still unknown. COVID-19 attaches to target host-cells by binding to the ACE2 receptor with it’s spike protein. ACE2 is highly expressed in the upper and lower respiratory tracts (but also on myocardial cells, renal epithelium, enterocytes and multiple endothelial cells of organs, and this may explain the extrapulmonary manifestations).

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🔢 Classification

There are many variants of COVID-19. They all follow the letters of the Greek alphabet. The current variants of concern (November, 2022) is omicron, BA.2, BA.4, BA.5.

However, former variants of concern were alpha and delta.

😷 Presentation

There is a spectrum of disease that can range from asymptomatic → life threatening disease. The patients at risk of more severe disease are the old, comorbid and also male patients.

Approximately 15% of patients will require hospitalisation. ~5% will need ITU support, and about 2-3% of cases are fatal.

There is an incubation period of up to 14 days, but symptoms usually present within 5 days.

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Initial presentation:

The initial presentation reflects viral replication in the upper respiratory tract:

  1. Fever
  2. Cough - usually dry, but may be productive in 1/4 of patients.
  3. Dyspnoea
  4. Anosmia
  5. Fatigue

Other symptoms include: sore throat, myalgia, headache, chest pain/tightness.

Extrapulmonary symptoms include:

  • Skin rash
  • Neurological symptoms - are rare, but associated with 3x more mortality. Delirium and confusion are some presentations of neurological complications.
  • GI symptoms - diarrhoea, nausea and vomiting is also rare but may be present, along with abdominal pain.

🚨 Complications

  • Thromboembolic complications - haemoptysis may be an indicator of PE. Major complications include venous sinus thrombosis which are clots within the venous sinuses of the brain.
  • Encephalopathy
  • Multisystem infammatory syndrome
  • ARDS - presents with tachypnoea, tachycardia, crackles or cyanosis.
  • Multi-organ dysfunction
  • 2º infection or super infection - pneumonia is common, more risk of ARDS.

🔍 Investigations

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Diagnosis:
  1. 🏆 PCR - an upper respiratory swab (nose and throat) is taken for PCR and the relative viral RNA levels are determined.
    1. If there is a negative result, but a high index of suspicion, the test should be repeated 24-48 hours later.
  2. 🥇 Lateral flow tests (rapid antigen tests) have been adopted, however, their sensitivity is not the best. Sensitivity is higher in the first week of symptoms (78.3%) but declines significantly in the second week (51%). These are an aid to diagnosis but should be used with caution.
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Imaging:
  • CXR - bilateral lower lung ground glass opacities are classical imaging findings.
  • Chest CT - more sensitive than CXR, also presents with ground glass opacifications.
Ground glass opacification on CXR
Ground glass opacification on CXR
Ground glass opacification on CT
Ground glass opacification on CT
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Laboratory findings:
  1. Lymphopenia ⬆️
  2. Elevated D-dimers ⬆️ - most likely due to acute lung injury or due to thromboembolic complications.
  3. Elevated ferritin ⬆️ - due to a host defence mechanism to deprive the virus of iron which is needed for the survival of COVID-19.
  4. Elevated lactate dehydrogenase ⬆️ - indicates tissue hypoperfusion.

🧰 Management

Management can be divided into mild, moderate, severe and critical COVID-19 management:

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Mild COVID-19:

🥇 Home isolation and monitoring is first-line. Symptomatic management and supportive care is also recommended

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Moderate COVID-19:

 🥇 Home isolation and monitoring is also all that is recommended.

Sotrovimab may be beneficial in patients who are at risk of developing severe disease. It is a monoclonal antibody against COVID-19.

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Severe COVID-19:

This is defined as: having clinical signs of pneumonia + one of the following:

→ RR >30

→ SpO2 <90%

→ Sever respiratory distress

🥇 Hospital admission is required and monitoring and management from a specialist team is needed in patients with risk of rapid deterioration

🥇 Oxygen therapy - targeting SpO2 >94%.

🥇 Dexamethasone and remdesivir should also be administered

This is coupled with:

  • + Symptomatic management (fluids, electrolytes, reassurance)
  • + VTE prophylaxis in the form of enoxaparin.

Tocilizumab (an IL-6 antagonist) may be used to remove the negative effects of the immune response, however, it increases the risk of secondary infection.

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Critical COVID-19:
  1. 🥇 ICU admission
  2. 🥇 VTE prophylaxis
  3. 🥇 High-flow nasal oxygen and consider mechanical ventilation. Mechanical ventilation carries a high-risk of mortality but outcomes appear to have improved.

Other things to consider are:

  1. Corticosteroids
  2. Antivirals such as remdesivir given IV.
  3. IL-6 inhibitor (tocilizumab)
  4. JAK inhibitor (baricitnib)
  5. Experimental therapies
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POST-COVID SYNDROME