What is COVID-19? Causes, symptoms, treatment, and complications

Written by Nicolas Perez Diaz, May 20, 2023.

COVID-19 is short for Coronavirus Disease 2019, which is often referred to as simply Coronavirus Disease. It is a disease caused by SARS-CoV-2, a virus which is a member of the Coronavirus family. It killed more than six million people in a global pandemic that ended recently.

It mainly spreads through droplets in the air from the coughs, sneezes, and exhalations of infected people. Exhalation is the act of breathing out air. When we talk, we exhale, therefore when people with COVID-19 talk, they are emitting droplets infected with SARS-CoV-2 into the air.  The virus can also survive on surfaces. If you touch a contaminated surface and then your face, you could become infected.

According to the World Health Organization (WHO):

“Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment. However, some will become seriously ill and require medical attention. Older people and those with underlying medical conditions like cardiovascular disease, diabetes, chronic respiratory disease, or cancer are more likely to develop serious illness. Anyone can get sick with COVID-19 and become seriously ill or die at any age. ”

Causes of COVID-19

The main reason for the spread of COVID-19 is human-to-human infection. The virus enters the human body through the mouth, nose, and eyes. Crowded environments, such as schools, workplaces, trains and buses during rush hours, and social gatherings are ideal environments for the rapid spread of SARS-CoV-2.

To lower the risk of transmission, it is essential to stick to recommended preventive practices and public health guidelines.

Regarding how humans get COVID-19, the Cleveland Clinic says the following:

“SARS-CoV-2, the virus that causes COVID-19, enters your body through your mouth, nose, or eyes (directly from the airborne droplets or from the transfer of the virus from your hands to your face). It then travels to the back of your nasal passages and mucous membrane in the back of your throat. It attaches to cells there, begins to multiply and moves into lung tissue. From there, the virus can spread to other body tissues.”

Signs and symptoms

COVID-19 signs and symptoms can range from mild to severe and may appear 2-14 days after exposure – in other words, COVID-19 has an incubation period of 2-14 days. The most common signs and symptoms include:

  • Cough (often persistent).
  • Fever.
  • Blocked/runny nose.
  • Body aches.
  • Diarrhea.
  • Fatigue
  • General body aches.
  • Headache.
  • Loss of appetite.
  • Loss of your sense of taste or smell.
  • Nausea, and sometimes vomiting.
  • Shortness of breath.
  • Sore throat.

Most people describe the signs and symptoms as similar to those of influenza (flu).

COVID-19 - Map showing global statistics

WHO image adapted by MedicalVocab.com.

Treatment for COVID-19

Currently, there is no specific antiviral treatment for COVID-19 (read about the antiviral treatments that can help some patients in the Harvard Health Publishing citation further down the page). Treatment focuses on symptom relief and preserving general health.

  • Treating Mild cases

The illness can be managed at home with rest, hydration, and OTC pain relievers and antipyretics (fever reducers). The letters OTC stand for over the counter. We can get OTC drugs without a doctor’s prescription. They contrast with prescription medications.

  • Treating Severe cases

Hospitalization may be required, where patients may receive oxygen therapy, medications to reduce inflammation, and other supportive measures.

  • Isolating yourself (for both mild and severe cases)

You should self-isolate until it has been five days since your first signs and symptoms appeared, you are improving, and you have not had a high temperature (fever) for at least 24 hours. For the next five days, you should wear a face mask, a well-fitting one, whenever you are around other people. On the fifth day, if you can, get a COVID test.

  • Treatment for people at risk of severe illness

According to Harvard Health Publishing:

“As of February 2023, there are three FDA-authorized antiviral treatments available to treat people who have mild or moderate symptoms of COVID-19 infection and have risk factors for severe illness. These treatments have been shown to reduce the risk of hospitalization and death in this population. They include a combination of nirmatrelvir and ritonavir (Paxlovid), molnupiravir (Lagevrio), and remdesivir (Veklury).”

“These medicines work by targeting specific parts of the SARS-CoV-2 virus to stop it from multiplying in the body.”


While most healthy individuals experience mild symptoms, COVID-19 can sometimes lead to severe complications, including:

  • Pneumonia – a severe lung infection caused by fluid accumulation and inflammation. It may result in severe cough, high fever, and breathing difficulties.
  • Acute respiratory distress syndrome (ARDS) – fluid starts to leak into the lungs because they are so damaged, which makes it harder and harder for oxygen to get into the bloodstream. The patient will probably need to be on a ventilator.
  • Acute respiratory failure – when the lungs do not pump enough oxygen for the body’s requirements. It is the leading cause of death for those infected with SARS-CoV-2.
  • Organ failure.
  • Blood clots are more likely to develop in patients with COVID-19 than those with flu.
  • Heart problems are a common complication.
  • Chronic fatigue – long-term severe tiredness. There is also brain fog, dizziness, and pain. Many patients have trouble thinking.

These complications are more likely to occur in older individuals, people with a weakened immune system, or those with pre-existing health conditions. It is important to protect yourself and others, even if you are at lower risk, to prevent the spread of the virus.

Prevention of COVID-19

Prevention plays a crucial role in controlling the spread of COVID-19. Here are some effective preventive measures:

  • Vaccination

COVID-19 vaccines have been developed and approved for emergency use. Vaccination significantly reduces the risk of severe illness, hospitalization, and death. It also helps protect the community.

  • Mask-wearing

Wear a well-fitted face-mask that covers your nose and mouth in public settings, particularly when social distancing is not possible. Masks help prevent respiratory droplets from being released into the air and reduce the risk of infection.

  • Social distancing

Maintain a distance of at least six feet from others, especially in crowded places. Avoid large gatherings and non-essential travel to minimize exposure.

  • Hand hygiene

Wash your hands frequently with soap and water (warm water if possible) for at least 20 seconds, especially after being in public spaces or touching surfaces. If soap and water are not available, use a hand sanitizer with at least 60% alcohol content.