COVID-19: Symptoms, Transmission, Tests & Treatment

Updated in January 2023

The SARS-CoV-2 virus, which is responsible for the coronavirus disease, or COVID-19, is a contagious illness that results in respiratory symptoms. While most people have mild to moderate symptoms, like a cough or headache, some people can experience high fever and have difficulty breathing, requiring hospitalization.

COVID-19 is mainly transmitted through droplets that are suspended in the air when an infected person coughs or sneezes.

Most cases resolve with just symptom management at home (e.g. treating a fever with acetaminophen, or resting to relieve a headache), however hospitalization may be required for those who develop more serious symptoms, like shortness of breath or altered level of consciousness. There are also newly available antiviral medications, like Paxlovid, to treat COVID-19 in those who are most at-risk or who are severely ill. 

Imagem ilustrativa número 1

Common symptoms

COVID-19 can cause various different symptoms that can vary from person to person. It can present like a mild flu in some people or a serious pneumonia in others. 

Normally, the first symptoms of COVID-19 appear 2 to 14 days after possible exposure to the virus. Common symptoms include:

  1. Dry and persistent cough
  2. Fever over 38ºC (or 100.4ºC)
  3. Excessive fatigue
  4. General muscle weakness or aches
  5. Headache
  6. Swollen or sore throat 
  7. Runny or stuffy nose
  8. Changes to intestinal flow, mainly diarrhea 
  9. Loss of taste or smell 
  10. Conjunctivitis
  11. Rashes

Because these symptoms are similar to a flu infection, COVID-19 can easily be misdiagnosed, therefore diagnosis through testing is essential. Some people may not have any symptoms, even with a positive test. 

In some cases, it is possible to notice changes to fingers or toes. This phenomenon is often referred to as “covid toes” but it is a condition called “pseudo-chilbains”. It is characterized by purple skin, swelling and vesicles that appear around the finger tips or toes that can be very painful or not cause pain at all. In general, people with “covid toes” do not present with other classic COVID-19 symptoms.

Severe symptoms

In more serious cases, initial symptoms can worsen in a short amount of time and the virus can become life-threatening. Severe symptoms of COVID-19 that require hospitalization are shortness of breath, chest pain and confusion.  

These more severe symptoms appear to emerge in people over the age of 60 and in those who have a weakened immune system, which can happen with an autoimmune disease, a transplant or chronic illness (like diabetes or high blood pressure). 

Online symptoms checker

Assess your risk for COVID-19 by entering your symptoms below

  1. 1. Do you have a headache or feel generally unwell?
  2. 2. Do you feel overall muscle pain?
  3. 3. Do you have excessive fatigue?
  4. 4. Do you have nasal congestion or a runny nose?
  5. 5. Do you have an intense, dry cough?
  6. 6. Do you feel intense pain or a persistent crushing feeling on your chest?
  7. 7. Do you have a temperature above 38ºC or 100.4ºF?
  8. 8. Do you have difficulty breathing or shortness of breath?
  9. 9. Are you lips or face slightly blue?
  10. 10. Do you have a sore throat?
  11. 11. Have you been somewhere with a confirmed case of COVID-19 in the last 14 days?
  12. 12. Have you been in contact with someone who might be infected with COVID-19 in the last 14 days?

COVID-19 transmission

Transmission occurs mainly through inhalation of droplets that are spread in the air from coughing or sneezing. This is called airborne or droplet transmission. It is also possible to contract COVID-19 from touching contaminated objects and then touching your face (especially the eyes, nose and mouth). This is called indirect contact transmission.

People are most likely to transmit the virus to others in the two days prior to symptoms appearing and in the three days following onset.

How it’s diagnosed

To diagnose COVID-19, you should be assessed by a health care provider who will evaluate your symptoms and complete a respiratory assessment. To confirm the virus, further lab testing is needed. 

There are many ways that COVID-19 can be tested, however the 3 most commonly used tests are:

1. PCR test

This is the gold standard for confirming the presence of COVID-19 due to its accuracy. A swab is inserted deep into the nostril to collect upper airway secretions, and is then sent to the lab to isolate virus cells. If virus cells are noted in the specimen, then this is considered to be a positive result. 

PCR testing in Canada is limited to certain populations (e.g. healthcare workers, older adults, and immunocompromised patients, among others) due to short testing supply and high demand from increasing virus prevalence. In the US, PCR testing is available to anyone with symptoms through private labs (ie. paying out of pocket), but can be covered through health insurance with a prescription from a health care provider. 

2. Rapid-Antigen Test

Similar to the PCR, this test also involves the collection of respiratory secretions with a nasal swab deep within the nostril, however the specimen is mixed on the spot with a solution and then placed on a testing cassette. It provides results within 15 minutes and can be completed at home. 

This test is usually recommended for people who do not have symptoms and want to check their health status for many reasons (e.g. due a possible recent exposure, prior to a social event, etc.). However, due to short global supply and testing capacity of the PCR test, many countries, like Canada and the UK, have opted to use rapid-antigen testing as a basis for diagnosis, no longer requiring PCR testing for confirmation. 

Rapid-antigen testing is available for purchase at select pharmacies and supermarkets, but can be available free-of-charge through government programs.

3. Antibody testing

With this type of test, a blood specimen is collected and analyzed in the lab to detect COVID-19 antibodies. While this test does not confirm a current or active infection, it is beneficial for knowing whether the person has contracted the virus in the past, or if they are immune to it. 

Treatment options

There is no specific treatment for COVID-19. Recommendations include symptom management with hydration, rest and light, balanced meals. You can take medication like acetaminophen to treat fever and other symptoms as directed by the doctor to facilitate treatment. Learn about how you can treat your cough with medicine and by using natural remedies. 

Some studies are currently being done to test the efficacy of various antiviral medications to treat the virus. Paxlovid, which is made by Pfizer, has recently been approved for use in the US, the UK and Canada to treat COVID-19. It contains two antiviral medications, nirmatrelvir and ritonavir, which are taken together to stop the virus from multiplying. Due to global supply shortage, it is available for use only by certain populations, such as older adults and immunocompromised patients. 

Remdesivir and sotrovimab are other medications that are available for treatment of the coronavirus. These are given through IV in hospital settings to patients who are at higher-risk.

In more serious cases, patients infected with COVID-19 can additionally develop a viral pneumonia, which can cause symptoms like intense pressure in the chest, high fever and shortness of breath. These patients are typically admitted to the hospital for oxygen therapy and monitoring of vital signs. 

Isolation rules

Although isolation is no longer mandated, public health authorities continue to stress the importance of isolation to prevent further transmission. In the USA, the CDC has advised that, regardless of vaccination status, 5 days of isolation is advised for those who have tested positive, although isolation should only be terminated on the 5th day if symptoms have resolved. If symptoms persist after the 5 days, isolation should continue for 10 days. 

In Canada, isolation guidelines are outlined by the provincial government, with each province and territory mandating their own laws and regulations based on their population needs. In Ontario, for example, those who have tested positive for the coronavirus are generally advised to isolate until symptoms have been improving for at least 24 hours. Meething with higher-risk groups (like older adults or people with chronic respiratory diseases) should be avoided for at least 10 days after initial symptoms. 

In the UK, those who test positive for COVID-19 are advised to isolate for 5 days, with the first day of symptoms counting as day 1. Isolation can terminate after 5 days if symptoms have improved and a rapid test shows a negative result. 

Preventing COVID-19

Although it is highly contagious, it is possible to decrease the risk of contracting COVID-19 by adopting certain behaviors. These include: 

  • Be up-to-date with your COVID-19 vaccine. 
  • Socially distance yourself from others, especially in crowded areas with close contact. You should maintain at least a 1 meter (or 3 foot) distance from others. 
  • If social distancing is not possible, wear a mask. 
  • Only participate in social events that are in well-ventilated areas (ie. outside is best) and where social distancing is possible.
  • Perform frequent hand hygiene by using alcohol-based sanitizer or washing your hands for 20-30 seconds in warm water and soap. 
  • Make sure you cover your mouth and nose when coughing or sneezing with a tissue or your bent elbow. 

It is important to remember that when you do cough or sneeze into a tissue, you should dispose immediately of the tissue and perform immediate hand hygiene.