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Symptoms, transmission and treatment


It is impossible to distinguish between COVID-19 and the flu based solely on symptoms, because they are too alike. A screening test must be performed to identify the presence of COVID-19. Due to an increase in the number of infections, PCR testing at the screening clinic is now reserved for certain higher priority clients. If you are not in a priority group, it is recommended that you do a rapid test at home. If you are unable to get rapid tests, self-isolate in accordance with Instructions for people with COVID-19.

The following symptoms apply to everyone, including babies aged 6 months and older. For babies aged under 6 months, call Info-Santé 811 or see a healthcare professional, if your child has symptoms, including a fever.

One of the following symptoms:

  • Fever:
    • from 6 years old: 38.1°C (100.6°F) and over (oral temperature)
    • 6 months to 5 years old: 38.5 °C (101.3 °F) and over (rectal  temperature)
  • Sudden loss of smell with no nasal congestion, with or without loss of taste
  • Cough (new or worsening)
  • Shortness of breath
  • Difficulty breathing
  • Sore throat

At least two of the following symptoms:

  • Runny nose nasal congestion (stuffy nose) for no known reason
  • Head ache
  • Profound fatigue
  • Muscle aches (not related to physical exertion)
  • Significant loss of appetite
  • Nausea or vomiting
  • Stomach ache
  • Diarrhea

When in doubt, call Info-Santé 811 or see a healthcare professional.

Symptoms can be mild or more severe like those associated with pneumonia.

Their duration varies depending on the severity of the illness, but they generally disappear in less than 14 days. In severe cases, symptoms can last for over a month.

Some people can spread the virus without knowing, even if they’ve been vaccinated, because they have no symptoms or have not yet developed them.

People most at risk of dying from complications are those:

  • with a weak immune system;
  • with a chronic disease such as diabetes or heart, lung and kidney disease;
  • age 70 and older.

However, the risk of death is highest for people aged 70 and older.

Development of symptoms

Symptoms develop on average from 5 to 7 days after contamination, but may appear over a 2 to 12 day period.

Note that you must self-isolate if you have symptoms of COVID-19. Consult the Instructions for people with COVID-19 symptoms page for guidelines appropriate to your situation.

A person may become infected with COVID-19 a second time. Most often, this happens in people with weakened immune systems. Most people who get COVID-19 recover and seem to be temporarily protected from being infected again with the virus.

Modes of transmission

The virus that causes COVID-19 is transmitted mainly through close contact lasting more than 15 minutes at a distance of less than two metres. Transmission can occur through aerosols, which are fine particles suspended in the air, especially indoors. Aerosols can be of different sizes and are emitted in variable quantities when the infected person breathes, talks, sings, coughs, sneezes, and so on. However, it is hard to determine exactly how an infected person passes the virus to others. When there is close contact, the virus can be picked up by direct contact, through particles in the air, or by contact with a surface contaminated by respiratory particles from an infected person. People can be infected by touching contaminated surfaces or objects, but this is not the main mode of transmission.

Certain variants seem to be transmitted more easily than others. Even people who have been vaccinated may pass on the virus if they are infected with certain variants, such as the Delta variant or the Omicron variant. That’s why it’s important to keep following the usual protection measures (physical distancing, mask wearing, and hand washing). See the Covid-19 vaccination page for more information.

Current knowledge does not allow us to identify precisely when COVID-19 is transmitted, but it is believed that a person infected with COVID‑19 may be contagious for 48 hours before symptoms appear. Researchers are still studying this question.

Person-to-person contact and levels of risk

See the Instructions for people who have been in contact with a case of COVID-19 for the instructions that apply according to the level of risk.

Other modes of transmission

In general, coronaviruses do not survive more than a few hours or days on objects. They can survive on surfaces for a few hours to several days. It mainly depends on the type of surface (for example, copper, cardboard, stainless steel, plastic), the temperature and ambient humidity. According to findings from a recent experiment, the virus might be able to survive up to:

  • 4 hours on copper;
  • 24 hours on cardboard;
  • 48 hours (2 days) on stainless steel;
  • 72 hours (3 days) on plastic.

At this time, there is no evidence to suggest that food is a likely source or route of transmission of COVID-19. You should continue to wash fruits and vegetables as usual and to follow good hygiene practices during food preparation.

Water treatment methods used in drinking water systems can neutralize the COVID-19 virus.

In Québec, there is no evidence to suggest that people are at risk of contracting COVID‑19 from animals or animal products. Furthermore, the World Health Organization (WHO) has stated that nothing indicates that coronavirus can be transmitted by mosquitoes.

Some viruses in the coronavirus family cause disease in animals, while others cause disease in humans. Coronaviruses that cause disease in humans can be spread by close contact between people. In rare cases, coronaviruses that infect animals can also infect people. Like SARS‑CoV‑2, the virus responsible for COVID‑19, two other coronaviruses are spread from animals to humans and cause or have caused serious disease in humans, namely, SARS‑CoV in 2003 and MERS‑CoV since 2012.

Preventive treatment

EvusheldTM is a medication available free of charge to prevent COVID-19 in certain individuals at high risk for complications.

This medication is not a vaccine replacement, but can provide additional protection, especially for people who are severely immunocompromised. This treatment is not intended for people who have contracted COVID-19.

For details on preventive treatment with EvusheldTM and to verify if you can benefit from it, consult the page Preventive treatment against COVID-19 (EvusheldTM).


Health Canada has approved the antiviral drug Paxlovid™ for the treatment of COVID-19. As the supply is limited, health and social services institutions will identify patients with very high risk of complications to be treated as a priority. For details on treatment with Paxlovid™ and to verify if you can benefit from it, see the Oral treatment against COVID-19 (Paxlovid™) page.

Prescription medicines should only be used when recommended by a healthcare professional.

You will find health advice to alleviate the symptoms in the self-care guide.

People infected by the virus, especially those who are seriously ill, should receive special care to relieve and treat their symptoms. For example, it may be necessary to administer acetaminophen if they have a fever, oxygen if they have trouble breathing, or an IV if they are dehydrated.

Some people with severe breathing difficulties will need additional supportive therapy and intensive care to help them breathe (e.g., tube in the airway and mechanical ventilator).

Numerous studies are underway to assess the effectiveness of medications in treating COVID-19, particularly antivirals.

No food, supplement, vitamin, or natural health product can protect you from COVID-19 or cure you of the disease.

Last update: May 9, 2022


Information on the website in no way replaces the opinion of a health professional. If you have questions concerning your health status, consult a professional.


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