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Brand Name
Vaxzevria (AstraZeneca COVID-19 Vaccine)
Common Name
COVID-19 vaccine (AstraZeneca ChAdOx1-S recombinant)
How does this medication work? What will it do for me?

This medication belongs to a group of medications known as vaccinesIt is used to prevent coronavirus disease 2019 (COVID-19) caused by the SARS-CoV-2 virus, for people 18 years of age and older.

This vaccine is a viral vector-based vaccine. It uses a harmless virus like an adenovirus, which causes the common cold, as a delivery system (vector) to deliver genes from the SARS-CoV-2 virus. After vaccination, the vector virus contained within the vaccine produces the spike protein which is found on the surface of the virus that causes COVID-19. This stimulates the body to produce its own antibodies against the spike protein (cells designed to attack that particular virus or bacteria). These antibodies remain in the body ready to attack any future virus that may cause infection.

The AstraZeneca COVID-19 vaccine has been granted authorization for sale under an Interim Order. This means that Health Canada has approved this medication to be marketed based on promising evidence of effectiveness, but the manufacturer must meet additional terms and conditions.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor.

How should I use this medication?

This medication is given as an intramuscular (into the upper arm) injection. Once prepared, the volume of the dose is 0.5 mL. Two injections are needed to provide protection from the virus. The second dose must be given 4 to 12 weeks after the first dose.

Based on information from clinical trials, the vaccine becomes effective approximately 3 weeks after the first dose and lasts up to 12 weeks. The second dose is necessary to establish maximum protection from COVID-19.

It is important for this vaccine to be given exactly as recommended by your doctor. If you miss an appointment to receive this vaccine, contact your doctor as soon as possible to reschedule your appointment. All vaccines should be added to your immunization record.

This medication should be stored in a refrigerator and protected from light. It may be kept at room temperature for up to 6 hours.

What form(s) does this medication come in?

Each 0.5 mL dose of colourless-to-slightly-brown, clear-to-slightly-opaque, sterile, particle-free, preservative-free, solution for intramuscular injection, contains 5 x 1010 viral particles encoding for the SARS-CoV-2 Spike (S) glycoprotein (GP). Nonmedicinal ingredients: disodium edetate dihydrate (EDTA), ethanol, L-Histidine, L-Histidine hydrochloride monohydrate, magnesium chloride hexahydrate, polysorbate 80, sodium chloride, sucrose and water for injection.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to any ingredients of the medication
  • have had an allergic reaction to a previous dose of this vaccine
  • have experienced episodes of capillary leak syndrome
  • have had a major blood clot occurring at the same time as having low levels of platelets (thrombocytopenia) after receiving a previous dose of this vaccine
What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • chills
  • diarrhea
  • dizziness
  • general feeling of being unwell
  • headache
  • mild fever
  • muscle or joint pain
  • nausea
  • redness, swelling, tenderness, or pain at place of injection
  • sleepiness
  • swollen lymph nodes
  • tiredness
  • vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • changes in your heartbeat
  • excessive sweating
  • itchiness
  • rash

Seek immediate medical attention if any of the following occur:

  • signs of blood clots (e.g., coughing up blood; pains in chest, groin, or leg – especially in calf of leg)
  • signs of capillary leak syndrome (e.g., rapid swelling of the arms and legs, sudden weight gain, feeling faint)
  • signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)
  • symptoms of a serious allergic reaction (such as hives, difficulty breathing, itchy rash on the hands or feet, or swelling of the face or throat)
  • unusual skin bruising or pinpoint round spots (away from the site of vaccination)

Be sure to mention any side effect to your doctor, as it may mean that you are allergic to the vaccine. If so, it would not be safe for you to have more doses of the same type of vaccine.

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.


November 9, 2021

Health Canada has issued information concerning the use of the AstraZeneca COVID-19 vaccine. To read the full Health Canada Advisory, visit Health Canada's web site at  www.hc-sc.gc.ca.

Previous advisories on the AstraZeneca COVID-19 vaccine were issued on June 29, 2021, April 14, 2021 and March 11, 2021.

Allergic reactions: Rarely, this vaccine may cause severe allergic reactions. For this reason, you may be asked to wait for a period of time after receiving the vaccine so that you can get medical care if you have an allergic reaction. If you notice the signs of a severe allergic reaction (hives; trouble breathing or swallowing; or swelling of the lips, face, throat, or tongue), get medical attention immediately.

Bleeding: People with bleeding disorders may experience bruising after receiving an intramuscular injection. Tell your doctor about any bleeding problems you may have and discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Immune system: As with any vaccine, this vaccine may not be as effective for people with a weakened immune system (such as those who are on chemotherapy, who have had an organ transplant, who are taking immune-suppressing medications, or who have HIV).

Other illness: If you have a high fever or other illness, discuss with your doctor about rescheduling your appointment to receive this vaccine after you have recovered. It is advisable to wait to receive this vaccine if you have an acute, severe illness with fever.

Vaccine protection: It is important to make sure you receive your second dose of this vaccine to ensure the most protection. As with any vaccine, this vaccine may not protect 100% of people who receive it.

Pregnancy: This vaccine should not be used during pregnancy unless the benefits outweigh the risks. If you discover you may have been pregnant when you received this medication, contact your doctor immediately.

Breast-feeding: It is not known if this vaccine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this vaccine have not been determined for children and adolescents under the age of 18.

What other drugs could interact with this medication?

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.

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