1. Coronavirus Disease
COVID-19

2. Introduction Coronaviruses are a large family of viruses.
Several coronaviruses are known to cause respiratory infections in humans ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) in 2003 and Severe Acute Respiratory Syndrome (SARS) in 2012.
COVID-19 is an infectious disease caused by the most recently discovered coronavirus. This new virus and disease were unknown before the outbreak began in Wuhan, China, in December 2019.

3. Nomenclature
On February 11, 2020, the WHO Director-General, Dr. Tedros Adhanom Ghebreyesus, announced that the disease caused by this new coronavirus was a "COVID-19," which is the acronym of "coronavirus disease 2019".
Initially, the new virus was called 2019-nCoV. Subsequently, the task of experts of the International Committee on Taxonomy of Viruses (ICTV) termed it the SARS-CoV-2 virus as it is very similar to the one that caused the SARS outbreak.

4. Incubation period
The “incubation period” means the time between catching the virus and beginning to have symptoms of the disease.
Most estimates of the incubation period for COVID-19 range from 1-14 days, most commonly around five days.

5. Structure

6. Description
Coronaviruses are positive-stranded RNA viruses with a crown-like appearance under an electron microscope (coronam is the Latin term for crown) due to the presence of spike glycoproteins on the envelope.
SARS-CoV-2 has round or elliptic and often pleomorphic form, and a diameter of approximately 60–140 nm. Like other Coronaviruses, it is sensitive to ultraviolet rays and heat.
Its single-stranded RNA genome contains nucleotides, encoding for 9860 amino acids. 
It has 89% nucleotide identity with bat SARS-like- CoVZXC21 and 82% with that of human SARS-CoV.

7. Contributed by Rohan Bir Singh, MD; Made with Biorender.com

8. Symptoms MOST COMMON MAY ALSO HAVE Fever Fatigue Dry Cough
Aches and Pains
Runny nose
Sore throat
Shortness of Breath
In critical cases,COVID-19 can cause severe pneumonia or a multiple-organ failure and can lead to death

9. Transmission
The disease can spread from person to person through small droplets from the nose or mouth of a person with COVID-19 coughs or exhales.
These droplets land on objects and surfaces around the person.
Other people then catch COVID-19 by touching these objects or surfaces, then touching their eyes, nose or mouth.
People can also catch COVID-19 if they breathe in droplets from a person with COVID-19 who coughs out or exhales droplets.

10. Transmission Flowchart
Primary Host
(Bats)
Intermediate Host
(Suspected as Pangolins)
Human Host
When the infected person cough or sneeze
Droplets containing virus in the air
Droplets land in the nose mouth and reach lungs
Droplets fall on objects
On fingers from touching
The droplets eventuallly get into nose and mouth
Transmission Flowchart

11. Diagnosis
The WHO recommends collecting specimens from both the upper respiratory tract (naso- and oropharyngeal samples) and lower respiratory tract such as expectorated sputum, endotracheal aspirate, or Broncho alveolar lavage.
In the laboratory, amplification of the genetic material extracted from the saliva or mucus sample is through a reverse polymerase chain reaction (RT-PCR), which involves the synthesis of a double-stranded DNA molecule from an RNA mold.
Once the genetic material is sufficient, the search is for those portions of the genetic code of the coronavirus that are conserved. Presence of the portions confirms the disease.

12. Treatment
There is no specific antiviral treatment recommended for COVID-19, and no vaccine is currently available.
The treatment is symptomatic, and oxygen therapy represents the major treatment intervention for patients with severe infection.
Mechanical ventilation may be necessary in cases of respiratory failure refractory to oxygen therapy, whereas hemodynamic support is essential for managing septic shock. 

13. Drugs under testing
While studies are on, and different countries try various combinations to treat its patients, the WHO launched a multicountry clinical trial to test four drug combinations that have yielded results – an experimental antiviral drug called remdesivir, the antimalarial drug chloroquine (or the related hydroxychloroquine),a combination of two HIV drugs (lopinavir/ritonavir), and those same two HIV drugs along with the anti-inflammatory interferon beta.

14. Prevention
Avoid close contact with subjects suffering from acute respiratory infections.
Wash your hands frequently, especially after contact with infected people or their environment.
People with symptoms of acute airway infection should keep their distance, cover coughs or sneezes with disposable tissues or clothes and wash their hands.
Individuals who are immunocompromised should avoid public gatherings.

15. Importance of social distancing
Social distancing includes ways to stop or slow the spread of infectious diseases.
It means less contact between you and other people.
Social distancing is important because COVID-19 is most likely to spread from person-to-person through direct close contact with a person while they are infectious or in the 24 hours before their symptoms appeared.
So, the more space between you and others, the harder it is for the virus to spread.

16. Effects in lungs
The infection reach the lungs, causing inflammation in their mucous membranes and damaging their air sacs. The inflammation hampers the lungs’ ability to oxygenate the blood.
The inflammation in the lungs, and their reduced efficacy, can cause them to fill with fluids, pus and dead cells, and cause an infection, leading to pneumonia.
Some people who are infected have difficulty breathing and require a ventilator, and for others, the lungs become so inundated with fluids that even with intervention, they die.

17. Effects in other organs
The virus can also enter the bloodstream, and may be able to infect the gastrointestinal system, causing symptoms like diarrhea and indigestion.
The infection can also directly damage organs including the heart, kidneys, and liver, and cause bone marrow to become inflamed. Small blood vessels may also be vulnerable to inflammation.
The body’s own immune response to the infection can cause inflammation and organ malfunction. It is still unclear if the brain is affected.

18. Replication

19. Severity
Mild An upper respiratory tract viral infection, including mild fever, cough (dry), sore throat, nasal congestion, malaise, headache, muscle pain, or malaise. Moderate Respiratory symptoms such as cough and shortness of breath (or tachypnea in children) are present without signs of severe pneumonia. Severe Fever is associated with severe dyspnea, respiratory distress, tachypnea (> 30 breaths/min), and hypoxia.

20. Stages
Stage 1 | Imported Cases: These are those who have travelled to virus-hit foreign countries and have come back.
Stage 2 | Local Transmission: These are those cases who have come in contact with patients who have a travel history.
Stage 3 | Community Transmission: Community transmission is when a patient not exposed to any infected person or one who has travelled to any of the affected countries tests positive. Large areas get affected when community transmission takes place.
Stage 4 | Epidemic: This is the last and the worst stage where the disease take the shape of an epidemic with no clear end point.

21. Comparison with other Respiratory Viral Infections
Disease
Flu
COVID-19
SARS
MERS
Incubation time
1-4 days
4-14 days*
2-7 days
6 days
Case Fatality Rate(CFR) %
~3.4%*
9.6-11%
34.4%
Basic Reproductive Number(R0)
1.3 * 3
Hospitalization Rate 2%
~19%*
Most cases
Community Attack Rate
10-20%
30-40%*
10-60%
4-13%
Disease Causing Pathogen
Influenza virus
SARS-CoV-2
SARS-CoV
MERS-CoV
*COVID-19 data as of March 2020.

22. Facts
Only wear a mask if you are ill with COVID-19 symptoms (especially coughing) or looking after someone who may have COVID-19. If you are not ill or looking after someone who is ill then you are wasting a mask.
The virus’s genetic makeup reveals that SARS-CoV-2 isn’t a mishmash of known viruses. Therefore, it is not a human made virus.
WHO is continually updating technical guidance for COVID-19, including recommendations on laboratory testing. Chest CT scan is also used in the diagnosis.

23. Facts(cont.) COVID-19 is a pandemic disease.
Epidemic-Widespread in a particular region or Country.
Pandemic-It is a larger epidemic that covers several countries or spread from one continent to another.
From the evidence so far, the new coronavirus can be transmitted in all climatic conditions including areas with hot and humid weather.
Viruses are considered as non-living outside the host cell due to its inability to replicate outside the host cell (obligate intracellular parasites).

24. Facts(cont.)
Older persons and persons with pre-existing medical conditions (such as high blood pressure, heart disease, lung disease, cancer or diabetes)  appear to develop serious illness more often than others.
Studies suggest that coronaviruses may persist on surfaces for a few hours or up to several days.
This may vary under different conditions (e.g. type of surface, temperature or humidity of the environment).
Antibiotics do not work effectively against viruses.

25. References https://www.who.int/health-topics/coronavirus
Chan JF, Kok KH, Zhu Z, Chu H, To KK, Yuan S, Yuen KY. Genomic characterization of the 2019 novel human-pathogenic coronavirus isolated from a patient with atypical pneumonia after visiting Wuhan. Emerg Microbes Infect. 2020;9(1):
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26. https://english. jagran
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Source for images
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27. Thank you