How COVID-19 spreads
COVID-19 spreads from an infected person to others through respiratory droplets and aerosols created when an infected person coughs, sneezes, sings, shouts, or talks. The droplets vary in size from large droplets that fall to the ground rapidly (within seconds or minutes) near the infected person, to smaller droplets, sometimes called aerosols, which linger in the air under some circumstances.
The relative infectiousness of droplets of different sizes is not clear. Infectious droplets or aerosols may come into direct contact with the mucous membranes of another person’s nose, mouth or eyes, or they may be inhaled into their nose, mouth, airways and lungs. The virus may also spread when a person touches another person (i.e., a handshake) or a surface or an object (also referred to as a fomite) that has the virus on it, and then touches their mouth, nose or eyes with unwashed hands.
Learn more about modes of transmission of COVID-19.
Difference between quarantine and isolate
People are asked to quarantine or isolate to help prevent the spread of COVID-19 to others. Although these two words are often thought to mean the same thing, there’s an important difference.
Quarantine
If you have no symptoms and any of the following apply to you, you must quarantine for 14 days (starting from the date you arrive in Canada):
- you’re returning from travel outside of Canada (mandatory quarantine)
- you’re travelling to a province or territory that’s enforcing 14-day quarantine for all inter-provincial travellers
- you had close contact with someone who has or is suspected to have COVID-19
- you’ve been told by the public health authority that you may have been exposed to COVID-19 and need to quarantine
Isolate
You must isolate if any of the following apply:
- you’ve been diagnosed with COVID-19, or are waiting to hear the results of a lab test for COVID-19
- you have symptoms of COVID-19, even if mild, and you’ve been:
- in contact with someone who has or is suspected to have COVID-19
- told by public health that you may have been exposed to COVID-19
- you’ve returned from travel outside Canada with symptoms of COVID-19 (mandatory)