COVID-19 (coronavirus disease): Spread, prevention and risks
On this page
- How COVID-19 spreads
- Preventing severe COVID-19 disease
- Risks of getting COVID-19
- Who is most at risk
- Recommendations for travellers
How COVID-19 spreads
COVID-19 can spread easily from person to person through infectious respiratory particles released into the air. Someone who has COVID-19 can spread it to others before showing symptoms or without developing symptoms.
You can get COVID-19 if:
- you breathe in the infectious particles
- the infectious particles or secretions (like saliva or mucus) come into direct contact with your eyes, nose or mouth
- for example, if someone with COVID-19 coughs or sneezes on you
- you touch your eyes, nose or mouth with unclean hands after you've touched infectious particles or secretions on:
- a contaminated surface or object
- another person (for example, through a handshake)
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Animals
Based on available information to date, animal-to-human transmission is very uncommon.
People with COVID-19 can spread the virus to animals during close contact. To prevent possible infection, anyone with suspected or confirmed COVID-19 should avoid contact with:
- household pets
- other animals, including feeding wildlife
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Food
There's currently no evidence to suggest that food is a source of COVID-19. There haven't been any confirmed cases of COVID-19 being spread through food or food packaging.
Follow safe food handling advice to help reduce your risk of foodborne illnesses.
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Preventing severe COVID-19 disease
Vaccination
Vaccination is one of the most important ways to protect yourself from developing serious complications from COVID-19. It's important to get the COVID-19 vaccinations recommended for you. The COVID-19 vaccines used in Canada are very effective at preventing severe illness, hospitalization and death from COVID-19.
Learn more:
- Approved COVID-19 vaccines
- Get vaccinated against COVID-19
- COVID-19: Vaccine safety and side effects
- Canada's COVID-19 vaccine supply and donation strategy
- Vaccines and treatments for COVID-19: Safety after authorization
Personal protective measures
In addition to vaccination, use personal protective measures to help protect yourself and others from COVID-19.
You can reduce your risk of getting or spreading COVID-19 by:
- staying home and limiting contact with others when you're sick, even if your symptoms are mild
- wearing a well-fitting respirator or mask
- wearing a mask is recommended if you have symptoms and must:
- be around others
- enter a public setting
- seek medical care
- wearing a mask is recommended if you have symptoms and must:
- opening windows and doors when possible to improve indoor air ventilation
- cleaning your hands regularly by:
- washing with soap and water for at least 20 seconds (preferred method if hands are visibly soiled) or
- using a hand sanitizer containing at least 60% alcohol for 20 seconds or until dry
- covering your coughs and sneezes with a tissue or your elbow instead of your hand
- avoiding touching your eyes, nose or mouth with unclean hands
- cleaning and disinfecting high-touch surfaces and objects regularly
Learn more:
- Personal protective equipment and medical supplies
- COVID-19: What to do if you or someone in your home is sick
- Respiratory infectious diseases: Mask use for reducing the spread
- Clean your hands to help reduce the spread of infectious diseases
- Respiratory infectious diseases: How to reduce the spread with personal protective measures
Risks of getting COVID-19
COVID-19 continues to spread at different levels in our communities, and outbreaks still occur. New variants of concern may also emerge.
COVID-19 immunity through vaccination and previous infection decreases over time.
We know that COVID-19 is most frequently transmitted through infectious respiratory particles released into the air by an infected person. This typically occurs when people are in close contact with someone who has COVID-19, especially when indoors. The risk of spread is higher if the person who is infected is also singing, shouting or breathing heavily (like when exercising) in these settings.
Some settings will be higher risk, including those that:
- are small
- are crowded
- have poor ventilation
- have people visiting for longer periods of time
Who is most at risk
Certain people are at an increased risk of being exposed to COVID-19, developing serious complications from COVID-19, or both. This includes:
- all adults 65 years of age or older
- residents of long-term care homes or other group living settings
- people living with an underlying medical condition, such as:
- asthma (moderate to severe)
- dementia
- diabetes
- heart disease
- high blood pressure
- kidney disease
- liver disease
- lung disease
- stroke
- obesity (body mass index [BMI] of 40 or more)
- Down syndrome
- people who are immunocompromised, including those who:
- have an underlying medical condition, such as cancer or HIV
- take medications that reduce the immune response, such as chemotherapy or corticosteroids
- had a solid organ or stem cell transplant
- people who are pregnant
- people from First Nations, Inuit or Métis communities
- healthcare workers and other care providers in a facilities and community settings
- members of racialized or other communities that face social and structural inequities
If you're at higher risk, it's even more important that you take action to reduce your risk of getting the virus. This means you should receive recommended vaccines and use personal protective measures in higher-risk settings.
Learn more:
- COVID-19: Pregnancy, childbirth and caring for a newborn
- COVID-19: What to do if you're at risk of more severe disease or outcomes (printable poster)
Recommendations for travellers
In general, it's important to talk to a health care provider or visit a travel health clinic preferably 6 weeks before your trip to get personalized health advice. Even if your travel date is coming up soon, it's still worthwhile to make an appointment.
Review the travel advice and advisories page for your destination. The 'Health' section has information on the health risks at your destination and the steps you can take to reduce those risks.
If you have symptoms of a respiratory illness, consider postponing travel plans until you're feeling better.
To prevent getting a COVID-19 infection when travelling, use personal protective measures.
How to reduce the spread of respiratory infectious diseases with personal protective measures
Learn more:
- Travel health notices
- Tips for healthy travel
- Symptoms of COVID-19
- If you become sick or injured while travelling outside Canada or after your return