COVID Flashcards
What is SARS-COV2 and what does it stand for?
Severe Acute Respiratory Syndrome from the Coronavirus 2
Illness caused by the COVID-19 virus
What other viruses does SARS-COV2 share genetic materials with?
SARS from 2002-2003 and MERS from 2012 which are 80% similar to it
Where did COVID-19 come from?
(Etiology, 3 points)
- Started in Wuhan, China - traced back to a fish/meat market
- Believed to have come from bats - 96.2% genetic similarity to bat coronavirus
- Underwent antigenic shift from bat to human, unknown if intermediate carrier was involved
What 6 components is the COVID virus made of?
- Spike Protein
- Hemagglutinin Esterase Protein
- Envelope Bilayer
- Nucleocapsid protein
- RNA (single strand)
- M-protein (membrane) and E-protein (envelope)
What are the current variants of concern (VOC)?
None
What are the current variants under monitoring (VUM)?
Anything containing the F456L spike mutation
What are the current variants being monitored (VBM)?
Omicron
Alpha
Beta
Gamma
What is the reproductive rate (R0)?
How many individuals a virus can be passed on to from 1 infected individual
What is the series interval (Si)?
The time it takes (in days) to pass on a virus to another individual
What are the 4 modes of transmission for COVID?
- Respiratory droplet
- Fomite - depends on surface
- Fecal-oral
- Vertical transmission
How long can COVID last on surfaces (as fomites)?
Copper + latex = 8 hours
Wood + glass = 5 days
How long can COVID respiratory droplets stay in the air?
Up to 3 hours
What percent of COVID transmission occurs through vertical transmission?
~3% occurs during later stages of pregnancy and in breastfeeding
What 4 risk factors increase risk of COVID-19 infection or mortality
Cardiovascular disease
Lung disease
Diabetes
Immunosuppression or cancer
What 3 elevated lab values would indicate increased risk of mortality?
- D-dimer
- Ferratin
- CK-MB
What are the 3 phases of COVIDs disease course?
Stage 1 - viral response
Stage 2 - pulmonary phase
Stage 3 - hyper inflammatory phase
Explain the viral response of COVIDs disease course:
The viral response includes the incubation and infectious periods
- person shows mild symptoms
- is contagious
Explain the pulmonary phase of COVIDs disease course:
- when the adaptive immune response occurs
- person experiences hypoxia and dyspnea
List the events of the hyper inflammation phase in COVIDs disease course (4)
- Disseminated intravascular coagulation
- cytokine storm
- ARDS
- multi-system organ failure
What are the target cells and target tissue of COVID?
Target cells: any cells that have an ACE2 receptor
Lungs are the main target area - alveoli have type 2 pneumocytes with ACE2 receptors
**other cells also have ACE2 receptors, which is why COVID produces a variety of symptoms
What is the co-receptor that COVID uses?
Transmembrane protease serine 2 (TMPRSS2)
Explain the cytokine storm
AKA Cytokine release syndrome
Whole bunch of WBC are activated through air but they then release a bunch of inflammatory cytokines which then activates more immune cells
– creates positive feedback loop
What 4 WBC are part of the cytokine storm?
Macrophages
Lymphocytes
Dendritic cells
Monocytes
What are the 4 effects of the cytokine storm?
- Act on vascular endothelium (VCAMS)
- Activate neutrophils
- Impaired coagulation
- Increase in chemical mediators
Explain how cytokines act on VCAMs.
The cytokines interleukin-1, 6, 8 tumor necrosis factor A (TNFA)
interferon gamma increase the expression of vascular cellular adhesion molecules which pull WBC out of vascular space into lungs
Explain the activated neutrophil step of the cytokine storm
Increased neutrophil activity results in increased release of reactive oxygen species (ROS) and proteases = damages surrounding cells
Explain the effects of damaged type 1 alveolar cells as a result of increased neutrophil activity
Damage to type 1 alveolar cells = impaired gas exchange
Hypoxia, SOB
Explain the effects of damaged type 2 alveolar cells as a result of increased neutrophil activity
Damage to type 2 alveolar cells = decreases surfactant = increases surface tension = alveolar collapse
*further impairs gas exchange
Explain how coagulation activity is impaired due to the cytokine storm
Increased pro-coagulants and decreased anti-coagulants results in possible clot and pulmonary emboli
What happens when alveolar cells are damaged? (think CNS)
They release chemical mediators which connect with receptors related to the vagus nerve = CNS stimulation = bronchioconstriction
What other body systems are affected by COVID?
Olfactory - loss of sense of taste + smell
Heart - damaged myocardial tissue
GI tract - N+V, diarrhea, abdominal pain
Kidneys - decreased function = decreased urine production
Liver - decreased function = metabolic disorders
What are pulmonary complications that can occur due to COVID?
pneumonia
pulmonary edema
pulmonary emboli
ARDS
What occurs with the lysis of cells with ACE2 receptors?
Increased angiotensin 2 production = affects blood pressure
Causes: pulm HTN, increased inflammation, increased vascular permeability
= results in acute lung injury
Explain disseminated intravascular coagulation?
A condition in which small blood clots develop throughout the bloodstream, blocking small blood vessels
Increase in clothing depletes the platelets and clotting factors needed to control bleeding = increased risk of excessive bleeding
What are two methods of diagnosing COVID?
- Nasopharyngeal swab
- Serology
Explain what a nasopharyngeal swab tests for?
A swab of cells and mucuous test from the present of RNA, it is the gold standard for testing but only has a 70% sensitivity
How does a serology test diagnose COVID?
Looks for the presence of antibodies
IgM = active infection
IgG = recovered from infection
Combined with RT-PCR, sensitivity increases to 95%
What are the treatments for mild-moderate COVID infection?
- inhaled corticosteroids
- antiretrovirals
What are the treatments for severe COVID infection?
- dexamethasone
- antiretrovirals
+/- supplemental O2
What are treatments for critically ill COVID infection?
- dexamethasone
- LMW heparin
- high-flow O2 or mechanical ventilation
- +/- immunosuppressants to prevent or lessen cytokine storm effects
