WLA VA:COVID19

Introduction

• Disease name = COVID-19
• Virus = SARS-CoV-2 (previously 2019-nCoV

Virology

• Coronaviruses are a common human pathogens (discovered in the1960s to cause the common cold).
  • During epidemics, they are the cause of up to one-third of community-acquired upper respiratory tract infections in adults; may cause diarrhea in infants and children as well)
• SARS-CoV-2 is a novel coronavirus (a new strain not previously identified in humans)
  • Likely primary source = bats
  • A betacoronavirus in the same subgenus as the severe acute respiratory syndrome (SARS) virus
  • Receptor-binding gene region is very similar to that of the SARS coronavirus (uses angiotensin-converting enzyme 2 [ACE2] for cell entry)
  • Middle East respiratory syndrome (MERS) virus, another betacoronavirus, appears more distantly related
• Viral survival time of SARS-CoV-2:
  • Stainless steel: persists for 3 hours (or longer)
  • Underscores the importance of environmental cleaning / disinfection
    • Cleaning gets rid of the proteins that would interfere with a disinfectants effectiveness
  • Note: studied in a simulated lab environment. Lab virions not covered in protein and mucus and other things that would mimic real life and that could prolong survival

Basic Epidemiology/Infectivity Data

• Expected patient outcomes (from data so far):
  • 80% have mild symptoms
  • 15% have severe disease requiring hospitalisation
  • 5% require mechanical ventilation
• Case fatality rate (CFR) = 2-4% (from Hubei data)
  • SARS ~ 10%
  • MERS ~ 35%
  • Seasonal flu ~ 0.1-0.2%
  • 1918 Pandemic Influenza ~ 2-3%
• R0 = 2.2 - 4.2
  • Where R0 = expected number of secondary cases produced by a single typical infection in a susceptible population (basic reproductive rate)
  • R0 for seasonal flu ~ 1.3
  • R0 for pandemic flu ~ 1.5-1.8
• Incubation: 5 days (median); range of 2-14 days
• Serial interval duration = 7.5 days
  • Serial interval refers to the time from illness onset in successive cases in a transmission chain

Ro Example

General Prevention Recommendations

• Exercise general infection precautions
  • Person-to-person transmission occurs with close contact (6 feet)
    • Direct contact with mucous membranes or respiratory droplets
    • Indirect: cough —> secretions left on surface —> 2nd person touches surface secretions and touches face & mucous membranes
  • Avoid touching your face (try it, it’s not easy)
  • Frequent Handwashing
    • Alcohol based hand sanitizer
    • Diligent hand wasing
      • 20 seconds minimum
      • Image shows commonly forgotten areas: thumb (ulnar aspect), fingertips, WRIST (Borrowed from WHO Hand Hygiene for Healthcare)
  • Wear a mask if you develop respiratory symptoms (fever, cough, rhinorrhea, congestion) to prevent spread
• Avoid unnecessary travel
• Stay home if symptomatic
  • Home care does not mean being out in the parks with other groups of people
  • Contact your supervisor: due to expected HCW shortages, minor symptoms may be allowed to continue working with adequate PPE to prevent infection spread