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Coronavirus COVID19

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Tohidul March 18, 2020


  • Description: acute infectious respiratory disease caused by infection with the coronavirus subtype SARS-CoV-2, first detected in Wuhan, China, in December 2019
  • Epidemiology: The greatest number of confirmed cases and deaths has been reported from mainland China, followed by South Korea, Iran, Italy, Japan, and Hong Kong. The disease is currently spreading worldwide.
  • Incubation period: 2–14 days
  • Transmission: person-to-person, primarily via respiratory droplets (sneezing and coughing) 
    • Direct contact transmission: especially hand-to-face contact 
    • Fomite transmission: not documented but conceivably possible, especially with objects and surfaces that may have recently come into contact with infected individuals 
      • Transmission via mail and packaged (imported) goods: There is no evidence to suggest that mail and packaged (imported) goods pose a risk for the spread of COVID-19.
    • Fecal-oral transmission: Evidence that both SARS-CoV and MERS-CoV are excreted fecally suggests that fecal-oral transmission is possible. [1]

The transmission of SARS-CoV-2 by asymptomatic individuals can occur, but individuals are most contagious when they are symptomatic.



  • Direct cytopathic effects
    • Virus-induced damage, particularly to the alveolar epithelium
    • Other organs, especially the liver and heart, can also be affected.
  • Dysregulated immune response: As in sepsis, there is an immune response involving the release of cytokines (IL-6) and the triggering of an acute inflammatory response. However, COVID-19 usually does not lead to hypotonia, a defining feature of sepsis.

Clinical features

  • Often asymptomatic 
  • Symptomatic cases
    • Most common: fever, fatigue, dry cough, anorexia, myalgia, and dyspnea
    • Less common: sputum production, rhinitis, sore throat, headache, diarrhea, and/or abdominal pain
  • The disease has a wide spectrum of severity, ranging from mild to critical.
    • Mild (∼ 80%)
      • Uncomplicated course without dyspnea
      • Lasts 1–2 weeks
    • Severe (∼ 15%)
      • Develops ∼ 5–7 days after symptoms begin
      • Indicates progression to pneumonia
      • Signs include dyspnea and hypoxia
      • Lasts 3–6 weeks
    • Critical disease (∼ 5%)
      • Involves signs of severe pneumonia (respiratory failure), shock, and possibly multiorgan failure
      • Lasts 3–6 weeks
Differential diagnoses


  • Polymerase chain reaction (PCR): swabs obtained using respiratory virus swab collection kits 
    • Upper respiratory tract
      • Nasal swab
      • Throat swab
    • Lower respiratory tract
      • Bronchial and tracheal secretions
      • Bronchoalveolar lavage
      • Sputum

Laboratory findings

  • CBC: lymphopenia (∼ 80%), leukopenia (∼ 30%), leukocytosis
  • LFTs: ↑ AST/ALT
  • ↑ CRP, ↑ LDH, ↑ ferritin, ↑ IL-6
  • ↑ D-dimer


  • Chest x-ray: usually bilateral, peripheral opacities in multiple lobes
  • Chest CT
    • Ground glass opacities that can progress to solid white consolidation in severe infection 
    • “Crazy paving” pattern


  • Current reports of the mortality rate range from ∼ 0.5 to 3%. 
  • Mortality is higher for older patients (> 65 years), especially those at risk of a severe course.
  • Risk groups include:
    • Individuals with chronic diseases, especially cardiovascular, pulmonary, or renal conditions
    • Immunosuppressed individuals

There is currently no evidence that infants and toddlers are at high risk for severe courses. Nevertheless, regardless of age, measures for infection control and prevention should be followed.

Counseling on infection control and preventive measures

  • Health care facilities should take hygiene and isolation measures in accordance with state or local health department recommendations and regulations. [5]
  • Health care providers should emphasize the following when counseling concerned patients:
    • Hand hygiene:
      • Hands should be washed with soap and water or disinfected with a virucidal hand disinfectant regularly and after contact with potentially virus-contaminated objects and infected persons 
      • Avoid touching the face: i.e., the eyes, nose, and mouth.
    • Respiratory hygiene and cough etiquette
      • Avoid coughing or sneezing in the direction of others!
      • Use tissues and discard these after use.
        • If tissues are unavailable, coughing and sneezing into the crook of the arm can help keep hands free of contamination.
      • Maintain 3–6 ft (at least an arm’s length) distance to coughing or sneezing persons.
    • Avoid exposure 
      • Avoid crowds of people (public transport, train stations, airports, mass events).
      • Avoid travel to areas of outbreak.
    • Masks
      • In PUIs and individuals with confirmed infection: useful for preventing the diffusion of respiratory secretions, e.g., during patient transports
      • In health care facilities or home care settings: crucial for health workers and persons taking care of an infected individual in close settings (in a health care facility or at home)
        • Surgical masks do not provide adequate protection in the setting of invasive diagnostics or those at high risk of exposure.
          • Surgical N95 respirators and protective eyewear are recommended for healthcare personnel that are potentially exposed to airborne and fluid hazards (e.g., during invasive procedures). [6]
          • Confirmed COVID-19 patients and PUIs can use standard N95 respirators.
          • If surgical N95 respirator bottlenecks occur, unvalved N95 respirators may be used with a face shield.
          • Respirators and masks should be used resourcefully with special consideration for health facility needs.
      • In the general population: Surgical masks are most likely ineffective and may even pose an additional risk of infection. 
Handwash technique