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
