COVID-19 is an infectious disease that first came to worldwide attention in December 2019. Cases of COVID-19 infection began to spread globally in increasing numbers and in March 2020, the World Health Organization (WHO) designated COVID-19 as a pandemic. To date, COVID-19 has affected countries all over the world, and it is continuing to spread.
The virus causing COVID-19 is officially known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It belongs to a larger family of viruses called coronavirus. Although coronaviruses can affect both animals and humans, only human coronaviruses are known to cause respiratory infections.
There are many genetic variations of the COVID-19 virus called variants. Variants can affect the spread of the virus, how serious an infection is and the protection that you receive from a previous infection, vaccines or treatments. Some variants of concern in Canada include Delta (B.1.617.2) and Omicron (B.1.1.529).
COVID-19 can spread directly from person to person through respiratory droplets. You can also come into contact with the virus through aerosols (droplets small enough to float in the air) created when an infected person coughs or sneezes. These aerosols linger in the air for long periods of time. You may also pick up the virus from touching infected surfaces and then touching your eyes, nose, or mouth.
People with highest risk of exposure include:
- Individuals who regularly interact with people who are not fully vaccinated
- Those who care for individuals who have or may have COVID-19
- People who work in environments with exposure to many individuals
- Individuals working in group settings such as correctional facilities, long-term care facilities and shelters or group residences
- Those facing social, economic or personal barriers that limit their ability to implement public health measures
Symptoms and Complications
People infected with COVID-19 may experience symptoms ranging from little-to-no symptoms to severe illness and death. Most infections are usually mild and begin up to 14 days after exposure.
Most common symptoms include:
- New or worsening cough
- Muscle aches
- Nausea, vomiting or diarrhea
Other symptoms include:
- Shortness of breath or difficulty breathing
- Sore throat
- Painful or difficulty swallowing
- Red eyes (conjunctivitis)
- Decreased appetite
- Loss of smell or taste
However, some people may develop other more severe complications, such as pneumonia or respiratory failure. The risk of severe illness from COVID-19 is higher for certain populations including individuals who are not fully vaccinated, pregnant women, adults aged 60 and older (risk increasing by age), people who have underlying chronic medical conditions (including heart disease, diabetes, lung disease), people living with obesity with a BMI of 40 or higher, and people with weakened immune systems.
In some cases, COVID-19 infection can lead to long-term symptoms that last for weeks or months after their initial recovery. This is known as post COVID-19 condition or long COVID. You can experience post COVID-19 condition regardless of the severity of your infection or whether or not you had symptoms while infected.
Post COVID-19 condition can affect people differently depending on their age. About 80% of adults and more than 50% of children experience post COVID-19 condition symptoms in the short term after recovering from their infection. Symptoms that commonly affect adults include:
- Memory problems
- Difficulty sleeping
- Shortness of breath
- Anxiety and depression
- General pain and discomfort
- Difficulty thinking or concentrating
- Posttraumatic stress disorder (PTSD)
Symptoms that commonly affect children include:
- Weight loss
- Muscle pain
- Difficulty sleeping
- Stuffy or runny nose
- Difficulty thinking or concentrating
Making the Diagnosis
If you feel you are experiencing symptoms of a COVID-19 infection you should self-isolate as directed by your local public health authority. Coronavirus infections can be detected by several types of testing methods, including molecular testing, antigen testing and antibody testing. Testing can be done by taking a nasal swab, a throat swab, an oral fluid swab or a saliva sample.
Treatment and Prevention
Most people with mild illness will recover without treatment. However, your health care provider may recommend some available medications to help provide comfort and alleviate symptoms of COVID-19.
Many medications to treat COVID-19 are currently being developed and tested. Health Canada has approved several treatments for COVID-19, including remdesivir and bamlanivimab. Some treatments, such as nirmatrelvir and ritonavir, can be taken orally at home. The availability and eligibility criteria for COVID-19 treatments may vary between across provinces and territories.
Currently, there are several COVID-19 vaccines authorized for use in Canada, including the Pfizer-BioNTech Comirnaty® COVID-19 vaccine and the Moderna Spikevax® COVID-19 vaccine. There are other vaccines currently under review, and Health Canada continues to closely monitor the vaccines that have been approved.
It’s recommended to get fully vaccinated against COVID-19 to lower your risk of getting infected as well as to lower your risk of other outcomes from severe infection such as hospitalization. Your local public health authority may recommend additional COVID-19 vaccine doses (i.e. booster doses) to provide better protection and to reduce the spread of the virus.
Since COVID-19 can spread from person to person, practising good hand hygiene is one of the most important things you can do to keep yourself from being infected. Wear a face mask whenever possible, especially when you’re out in public settings. Avoid touching your eyes, nose, and mouth with unclean hands. You should try to minimize your chances of being exposed to the virus by avoiding contact with people who are sick. If you are sick, you should cover your nose and mouth when sneezing and coughing.