If you have a fever or any other symptoms of COVID-19 or if you have received instructions from Public Health to self-isolate because of COVID-19, you must postpone getting vaccinated.


The following viral vector-based vaccines are currently authorized in Québec:

  • The Janssen vaccine, approved for men age 30 or over, women age 60 and over as well as some people age 18 and over. However, this vaccine is not distributed in Québec;
  • The AstraZeneca or Serum Institute of India (SII) Covishield vaccine, authorized for people age 18 and over in any of the following situations:
    • those for whom messenger RNA vaccines are contraindicated
    • those who refuse a messenger RNA vaccine

AstraZeneca and Covishield vaccines are considered equivalent, since they are produced using the same formula, that is, the formula provided by AstraZeneca, following a technology transfer to SII.

Where to get vaccinated
See the COVID-19 vaccination campaign page to find out the procedure for getting vaccinated.

How the vaccine works and ingredients

Vaccination prepares your body to defend itself against any microbes it may encounter.

The virus that causes COVID-19 is composed of a strand of genetic material, RNA (ribonucleic acid), surrounded by an envelope. On the surface of the virus, there are proteins, including the S protein (spike protein) which gives it its crown shape, hence its name coronavirus. The S protein allows the virus to infect cells in the human body.

COVID-19 viral vector-based vaccines block the S protein, preventing the virus from entering and infecting human cells.

The Janssen vaccine contains:

  • a tiny quantity of adenovirus;
  • salts (2-hydroxypropyl-β-cyclodextrin, citric acid monohydrate hydrochloride, sodium chloride, sodium hydroxide, sodium citrate dihydrate);
  • solvents (ethanol, Polysorbate 80).

AstraZeneca and Covishield vaccines contain:

  • a tiny amount of adenovirus;
  • salts (L-histidine hydrochloride monohydrate, magnesium chloride hexahydrate, sodium chloride, disodium edetate dihydrate);
  • amino acids (L-histidine)
  • solvents (ethanol, polysorbate 80)
  • sugar (sucrose).

COVID-19 vaccines and fetal cells

Like all vaccines administered in Québec, the Janssen vaccine, the AstraZeneca vaccine and the Covishield vaccine do not contain cells or tissues derived from humans or animals.

Since viruses replicate only in human or animal cells, these cells are essential for making vaccines. All human cells used to produce viral vaccines come from the kidney tissues of two fetuses aborted in 1973. Cells from these tissues have been replicated in the laboratory for nearly 50 years and no additional fetal tissue has been added to the cell line. Small samples of these tissues are used to produce the cells needed to make vaccines. During purification of the vaccine, all the human cells used are removed.

Number of doses

The vaccination schedule for the Janssen vaccine comprises a single dose. This vaccine is administered by intramuscular injection. It is currently not being distributed. A booster dose of the COVID-19 vaccine is recommended for people who have only received the Janssen vaccine. See the section on booster doses of the COVID-19 vaccine.

The vaccination schedule for the AstraZeneca and Covishield vaccines comprises two doses. Experts in Québec recommend that people age 18 and over who have received the AstraZeneca or Covishield vaccine as their first dose receive the Pfizer or Moderna for their second dose. The 2nd dose of the AstraZeneca and Covishield vaccines is required for long-term protection. Both doses are administered intramuscularly. See the section Second dose for people who received the Covishield or AstraZeneca vaccines to learn more.

A booster dose of COVID-19 vaccine is recommended for those vaccinated only with a Janssen, AstraZeneca, or Covishield vaccine. See the COVID-19 vaccine booster dose section.

For people with a weakened immune system or on dialysis, a third dose is necessary, preferably with a messenger RNA vaccine. For further information, see the see the Additional or booster dose of COVID-19 vaccine.

People who received an AstraZeneca or Covishield vaccine for the 1st dose could receive a messenger RNA vaccine (Pfizer or Moderna) for their 2nd dose. Go to the Second dose of COVID-19 vaccine page for more information.

People in good health who have had COVID-19 before receiving the vaccine only need one dose of a messenger RNA vaccine. For more information, see Vaccination for people who have had COVID-19 on the COVID-19 vaccination page.

Vaccine efficacy

The Janssen vaccine is 67% effective in preventing the disease and 77% effective in preventing hospitalization.

The AstraZeneca and Covishield vaccines are about 60% to 80% effective in preventing COVID-19. The second dose is needed to further reduce the virus’s ability to spread and to strengthen and prolong immunity. Québec authorities recommend that people age 18 and over who received AstraZeneca or Covishield vaccine for their first dose be given Pfizer or Moderna vaccine for their second. Getting Pfizer or Moderna vaccine for the second dose yields a better immune response than two doses of AstraZeneca or Covishield.

Currently, there is no efficacy data in preventing illness or hospitalizations with the Omicron variant after two doses.

Vaccine safety

See the Vaccine safety section on the COVID-19 vaccination page.

Symptoms after vaccination

Vaccination may cause symptoms such as redness at the injection site. Other problems may arise by chance and are unrelated to vaccination, such as a cold or gastroenteritis.

Most reactions are mild and short-lived. Reactions are more common after the 1st dose. Taking fever medication before vaccination is not recommended.

The vaccines cannot cause COVID-19 because they do not contain the SARS-CoV-2 virus responsible for the disease. However, a person who has been in contact with the virus in the days prior to or following vaccination may still develop COVID-19. It is important to continue to follow the health instructions until most of the population has been vaccinated.

Nature and frequency of known reactions caused by the Janssen vaccine


Known reactions caused by the vaccine

Very often
(less than 50% of people)
  • Pain or sensitivity at the injection site
  • Fever
  • Headache, fatigue
  • Nausea
  • Muscle pain
(less than 10% of people)
  • Itching, swelling, heat, or redness at the injection site
Very uncommon
(1 person in 100,000)
  • Guillain-Barré syndrome (gradual and irreversible paralysis that may cause lasting effects)
In rare cases
(1–9 people per million)
  • Blood clots with decrease in blood cells that help clotting within 4–20 days after vaccination

Nature and frequency of possible reactions to AstraZeneca or Covishield vaccines


Possible reactions to vaccines

In most cases
(more than 50% of people)

  • Pain or tenderness at the injection site
  • Headache, fatigue

Very often
(less than 50% of people)

  • Itching, swelling, warmth, redness or bruising at the injection site
  • Chills, discomfort, nausea
  • Muscle pain
  • Joint pain
(less than 10% of people)
  • Fever
  • Diarrhea (Covishield vaccine only)
Very uncommon
(1 to 9 people in 100,000)
  • Blood clots with decrease in blood cells that help clotting within 4–20 days after the 1st dose
  • Guillain-Barré syndrome
In rare cases
(1–9 people per million)
  • Blood clots with decrease in blood cells that help clotting within 4–20 days after the 2nd dose

Chills, discomfort, fatigue, muscle pain, and headaches occur more frequently after the 1st dose of the AstraZeneca or Covishield vaccines.

What to do after vaccination

Recommendations to follow in the minutes after vaccination

Wait 15 minutes before you leave the place where you were given the vaccine. If an allergic reaction occurs, the symptoms will appear a few minutes after you get vaccinated.

If you have side effects, tell the person who gave you the vaccine immediately. They can treat you there.

Recommendations to follow at home

If you experience redness, pain or swelling at the injection site, apply a cold damp compress.

Use medication for fever or discomfort after vaccination only if you have symptoms. Furthermore, taking anti-inflammatories such as ibuprofen or Aspirin after vaccination does not reduce the risk of thrombosis.

When to consult

Consult a doctor if any of the following apply to you:

  • You have serious or unusual symptoms.
  • Your symptoms get worse instead of better.
  • Your symptoms last more than 48 hours.

See a doctor quickly or contact Info-Santé 811 if you observe one or more of the following symptoms in the days after you get vaccinated:

  • shortness of breath;
  • severe headache or headache that lasts a few days;
  • blurred vision;
  • chest pain;
  • swollen legs;
  • abdominal pain;
  • skin bruising.

If you have symptoms of COVID-19 and you are not a priority client, it is recommended that you do a rapid test at home. If you are unable to get rapid tests, self-isolate respecting the Instructions for people with COVID-19.

Health instructions

The start of vaccination does not mean the end of health measures. It will take several months to protect a sufficiently large proportion of the population. It is essential to continue to follow the health instructions until further notice.

Why continue to protect yourselves after you’ve been vaccinated against COVID-19?