Viruses are ultra-microscopic, non-cellular living particles, composed solely of a nucleic acid (DNA or RNA) core, surrounded by a protein envelope called capsid.

Coronaviruses are a family of viruses that can cause illnesses such as the common cold, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). In 2019, a new coronavirus was identified as the cause of a disease outbreak that originated in China. There are many different kinds, and some cause disease. A newly identified type has caused a recent outbreak of respiratory illness now called COVID-19. Coronaviruses are a family of enveloped, single-stranded, positive-strand RNA viruses classified within the Nidovirales order.

The genome size of coronaviruses ranges from approximately 26 to 32 kilobases, one of the largest among RNA viruses. They have characteristic club-shaped spikes that project from their surface, which in electron micrographs create an image reminiscent of the solar corona from which their name derives.  These are a group of related viruses that cause diseases in mammals and birds. In humans, coronaviruses cause respiratory tract infections that can range from mild to lethal. Mild illnesses include some cases of the common cold (which has other possible causes, predominantly rhinoviruses), while more lethal varieties can cause SARS, MERS, and COVID-19. There are yet to be vaccines or antiviral drugs to prevent or treat human coronavirus infections.

The virus is now known as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease it causes is called coronavirus disease 2019 (COVID-19). In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic. Public health groups, including the U.S. Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO), are monitoring the pandemic and posting updates on their websites. These groups have also issued recommendations for preventing and treating the illness.

 How does the new coronavirus spread?

Researchers know that the new coronavirus spread through droplets released into the air when an infected person coughs or sneezes. The droplets generally do not travel more than a few feet and fall to the ground (or onto surfaces) in a few seconds — this is why social and physical distancing effectively prevents the coronavirus spread.

How did this new coronavirus spread to humans?

COVID-19 appeared in Wuhan, a city in China, in December 2019. Although health officials are still tracing the exact source of this new coronavirus, early hypotheses thought it may be linked to a seafood market in Wuhan, China. Some people who visited the market developed viral pneumonia caused by the new coronavirus. A study that came out on Jan. 25, 2020, notes that the individual with the first reported case became ill on Dec. 1, 2019, and had no link to the seafood market. Investigations are ongoing as to how this virus originated and spread.

Symptoms

Signs and symptoms of COVID-19 may appear two to 14 days after exposure and can include:

• Fever
• Cough
• Shortness of breath or difficulty breathing

Other symptoms can include:

• Tiredness
• Aches
• Runny nose
• Sore throat
• Headache
• Diarrhea
• Vomiting

Some people have experienced the loss of smell or taste.

The severity of COVID-19 symptoms can range from very mild to severe. Some people may have no symptoms at all. People who are older or who have existing chronic medical conditions, such as heart disease, lung disease or diabetes, or who have compromised immune systems may be at higher risk of serious illness. This is similar to what is seen with other respiratory illnesses, such as influenza.

When to see a doctor ?

If you have COVID-19 symptoms or you’ve been in contact with someone diagnosed with COVID-19, contact your doctor or clinic right away for medical advice. Tell your health care team about your symptoms and possible exposure before you go to your appointment.

If you have emergency COVID-19 signs and symptoms, such as trouble breathing, chest pain or pressure, confusion, or blue lips or face, seek care immediately. If you have respiratory symptoms but you are not and have not been in an area with ongoing community spread, contact your doctor or clinic for guidance. Let your doctor know if you have other chronic medical conditions, such as heart disease or lung disease. As the pandemic progresses, it’s important to make sure health care is available for those in greatest need.

Causes

Infection with the new coronavirus (severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). It’s unclear exactly how contagious the new coronavirus is. Data has shown that it spreads from person to person among those in close contact (within about 6 feet, or 2 meters). The virus spreads by respiratory droplets released when someone with the virus coughs, sneezes or talks. It can also spread if a person touches a surface with the virus on it and then touches his or her mouth, nose or eyes.

Risk factors

Risk factors for COVID-19 appear to include:

• Recent travel from or residence in an area with ongoing community of coronavirus spread as determined by CDC or WHO
• Close contact with someone who has COVID-19 — such as when a family member or health care worker takes care of an infected person

Complications

Although most people with COVID-19 have mild to moderate symptoms, the disease can cause severe medical complications and lead to death in some people. Older adults or people with existing chronic medical conditions are at greater risk of becoming seriously ill with COVID-19.

Complications can include:

• Pneumonia in both lungs
• Organ failure in several organs

Prevention

Although there is no vaccine available to prevent infection with the new coronavirus, you can take steps to reduce your risk of infection. WHO and CDC recommend following these precautions for avoiding COVID-19:

• Avoid large events and mass gatherings.
• Avoid close contact (within about 6 feet, or 2 meters) with anyone who is sick or has symptoms.
• Keep distance between yourself and others if COVID-19 is spreading in your community, especially if you have a higher risk of serious illness.
• Wash your hands often with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer that contains at least 60% alcohol.
• Cover your mouth and nose with your elbow or a tissue when you cough or sneeze. Throw away the used tissue.
• Avoid touching your eyes, nose and mouth.
• Avoid sharing dishes, glasses, bedding and other household items if you’re sick.
• Clean and disinfect high-touch surfaces daily.
• Stay home from work, school and public areas if you’re sick, unless you’re going to get medical care. Avoid taking public transportation if you’re sick.

Diagnosis

Diagnosis may be difficult with only a physical exam because mild cases of COVID-19 may appear similar to the flu or a bad cold. A laboratory test can confirm the diagnosis. To test for COVID-19, a health care provider uses a long swab to take a nasal sample. The sample is then sent to a lab for testing.

Treatment

Currently, no antiviral medication is recommended to treat COVID-19. Treatment is directed at relieving symptoms and may include:

• • Pain relievers (ibuprofen or acetaminophen)
  • Cough syrup or medication
  • Rest
  • Fluid intake

By: Surakchya Koirala
Lecturer, Nobel College