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Symptoms, transmission and treatment (COVID-19)

COVID-19 is an infection caused by the SARS-CoV-2 coronavirus.


The symptoms presented below do not apply to babies under 6 months of age. Consult Info-Santé 811 or a doctor if your child under 6 months presents symptoms, including fever.

Have one of the following symptoms:

  • Fever:
    • 6 years or older: 38.1°C (100.6°F) or higher (oral temperature)
    • 6 months to 5 years: 38.5°C (101.3°F) or higher (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

Or two of the following symptoms:

  • Runny nose or nasal congestion (stuffy nose) for no known reason
  • Headache
  • Extreme fatigue
  • Generalized muscle pain (not related to physical effort)
  • 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 light or more severe, like those associated with pneumonia. Their duration varies depending on the severity of the illness, but they generally subside in less than 14 days. In severe cases, symptoms can last for over a month. Some people can develop long COVID-19, which means they experience persistent symptoms or long-term complications following a COVID-19 infection.

General notice

It is not possible to differentiate between COVID-19 and the flu based on symptoms alone because the symptoms are too similar. A screening test must be performed to identify the presence of COVID-19. The NAAT tests conducted in screening clinics are reserved for priority groups. If you are not in one of the priority groups, it is recommended that you perform a rapid test.

People at risk

People most at risk of dying from complications are those:

  • aged 70 and older;
  • with a compromised immune system;
  • with a chronic disease such as diabetes, heart, lung, liver or kidney disease;
  • with another problem identified by the attending physician.

Development of symptoms

Symptoms develop on average from 5 to 7 days after contamination, but may appear over a 2 to 14 day period. For the Omicron variant, which is currently circulating in Quebec, the symptoms appear on average from 2 to 4 days after contamination.

A person can be infected with COVID-19 more than once. Most people who are infected with COVID-19 recover and seem to be temporarily protected from being infected again with the virus.


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:

  • by direct contact with secretions from the nose or mouth of an infected person, through kissing, for example;
  • through aerosols in the air. These are fine particles suspended in the air, especially indoors. Aerosols are emitted in variable quantities when the infected person breathes, talks, sings, coughs, sneezes, etc.;
  • by contact with a surface contaminated by the secretions of an infected person. However, this is not the main mode of transmission.

People can spread the virus without knowing it, even if they are vaccinated, because they have no symptoms or no symptoms have developed yet.

Current knowledge prevents us from specifying exactly how long people infected with COVID-19 remain contagious. However, it is thought that a person infected with COVID-19 may be contagious 48 hours before the onset of symptoms, and may remain contagious up to 10 days. Research is still underway.

Other modes of transmission

There is currently no evidence to suggest that food is a likely source or route of transmission of COVID-19.  Washing fruits and vegetables as usual and following good hygiene practises during food preparation are still recommended.

The treatment methods used in the drinking water distribution systems are able to neutralize the virus that causes COVID-19.

The risk that people can contract COVID-19 through animals is very low and there is no evidence to suggest a risk of transmission through animal products. Moreover, the World Health Organization has stated that, to date, there is no information or evidence that the coronavirus can be transmitted by mosquitoes.

Certain viruses in the coronavirus family cause illness in animals and others in humans. In rare cases, coronaviruses that infect animals can also infect people. Like SARS‑CoV‑2, which is responsible for COVID‑19, two other coronaviruses originated in animals and cause or have caused serious illness in humans, namely SARS‑CoV, in 2003, and MERS‑CoV, since 2012.


Most people infected by the COVID-19 virus recover without any particular treatment. You can ease your symptoms by following the advice at Self-Care Guide - COVID-19. See also the document Do I need to consult if I have COVID-19? (PDF 162 Kb) to know when to consult a health professional.

People at risk of developing serious complication can access to the antiviral drug PaxlovidTM for the treatment of COVID-19. For details on this treatment and to verify if you can benefit from it, see the Oral COVID-19 treatment (PaxlovidTM) page.

Prescription medication should only be used on the recommendation of a health professional. No food, supplement, vitamin, or natural health product can protect you from COVID-19 or cure you of the disease.

Treatments in case of complications

People infected by the virus can become seriously ill and must 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).

Protection and prevention

Vaccination offers protection from COVID-19 complications. For further information, see the Vaccination against COVID-19 page.

Some COVID-19 variants seem to be transmitted more easily than others. People who are vaccinated can also spread the virus if they are infected. In this context, it is essential that we take steps to limit the spread of respiratory infectious diseases, such as physical distancing, mask wearing and hand washing.

Last update: October 6, 2023


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