Corona virus disease (CO-VI-D)
Also named SARS-CoV-2
| Structural Protein | Functional Protein |
|---|---|
| Nucleocapsid Protein (N) | Bound to RNA genome to make up nucleocapsid |
| Spike Protein (S) | Critical for binding of host cell receptors to facilitate entry of host cell |
| Envelop Protein (E) | Interacts with M to form viral envelop |
| Membrane Protein (M) | Central organizer of CoV assembly, Determines shape of viral envelop |
Risks
- High-risk groups
- Elderly above 50
- With underlying diseases, e.g. diabetes, Parkinson’s disease, cardiovascular diseases
- Healthcare workers
From data collected from China, 80 years old above have a death rate of 14.8%
| SARS | MERS | COVID-19 | |
|---|---|---|---|
| Fatality rate | 9.6% | 34.4% | < 3% |
Mortality in most cases are in elderly and individuals with co-morbidities or weakened immune system.
Symptoms
Usually appear 2-14 days after exposure
For SARS it is 1-2 days
- Fever
- Cough
- Shortness of breath
Spread
- person-to-person via respiratory droplets among close contacts
- Infectious secretions, e.g. sputum, serum, blood, and respiratory droplets
2 meters (6 feet) from a patient for a prolonged period (~ 15mins) of time
Prevention
Hand
In descending order (good to bad)
- Alcohol-based hand rub
- Antimicrobial soap
- Plain soap
Mask
- Tight seal
- Cloth mask over surgical mask (if want to use 2 masks)
| N95 | KN95 | Surgical and Cloth | Surgical | Cloth | |
|---|---|---|---|---|---|
| Filter | 95% | 90-95% | 89% | 85% | 69% |
Testing
RT-PCR
CT value refers to the number of cycles which fluorescence of PCR product is detectable over and above the background signal (virus can be detected)
A measure of transmission potential (infectivity)
- COVID -ve: CT > 35 and asymptomatic
- COVID +ve: CT < 35
Lower CT, higher viral load
Lower CT cut-off, more relaxed (since lower CT means a higher viral load is needed)
CT has no correlation with severity, it is the viral load in the throat but not in the lungs
Sensitivity from 66% to 80% mostly because of sample collection problem, therefore more false negatives
RAT Kit
A sample of secretions deep within your nose is tested for the presence of antigens specific to the SARS-CoV-2 virus
Antigens are nucleocapsid proteins on the surface of the coronavirus
The sensitivity of RAT is lower than RT-PCR because there is no amplification process
So RAT can only be used for initial mass screening, not a conclusive diagnosis
Chest X-ray
- More white areas
- More noise
- Smaller chest
Effectiveness ranking: chest x-ray, pulse oximeter, infra-red thermometer
Vaccines
Sinovac
Since virus replicate very quickly, injecting inactivated virus might not be the safest option.
Pfizer and Moderna (mRNA)
Uses mRNA which teach human cells to make spike protein, safer.