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Immunization

COVID-19 vaccines – viral vector-based

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​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Immunization protects you from dis​ease.
​​Get protected, get immunized.

  • Vaccines make your immune system stronger. They build antibodies to help prevent diseases.
  • Immunization is safe. It's much safer to get immunized than to get this disease.​​

What are COVID-19 vaccines?

COVID-19 vaccines protect against the SARS-CoV-2 virus (also known as COVID-19). The virus causes an infection in the lungs and airways and is a type of respiratory illness. Go to ahs.ca/covid to learn more about COVID-19.

There are 2 types of COVID-19 vaccines approved for use in Canada:

How do viral vector-based vaccines work?

Viral vector-based vaccines use a harmless virus (that isn’t COVID-19) to carry information about the virus that causes COVID-19. This virus won’t give you COVID-19. It shows your cells how to make a spike protein, like the one that’s on the surface of the COVID-19 virus. This protein triggers your immune system to make antibodies against it. If you have contact with the real COVID-19 virus, these antibodies will be ready to protect you and fight the virus.

Who can get a viral vector-based COVID-19 vaccine?

You can get a viral vector-based COVID-19 vaccine if you’re age 18 years or older and you can’t get or don’t want an mRNA COVID-19 vaccine. Everyone is at risk of COVID-19. COVID-19 vaccines are free.

How well do COVID-19 vaccines work?

If you’re healthy and get all the doses you need, COVID-19 vaccines give you very good protection against COVID-19 infection. 

Two doses of the mRNA vaccines give more protection than 2 doses of the AstraZeneca/COVISHIELD vaccine or 1 dose of the Janssen vaccine.​ All the vaccines work very well to lower your risk of getting seriously ill and of needing to be in the hospital.​

Even if you’ve had a COVID-19 vaccine, it’s still important to follow public health measures to prevent the virus from spreading. Go to ahs.ca/covid for the most up-to-date information.

How many doses of viral vector-based COVID-19 vaccine do I need?

If you get the AstraZeneca/COVISHIELD vaccine, you need at least 2 doses to be considered fully immunized. These doses are called your primary series.

If you get the Janssen vaccine, at this time you need only 1 dose. But it's likely that in the future you'll need a second dose of Janssen vaccine for better protection and to complete your primary series. ​

Some people may need more doses. See the following information and visit alberta.ca/covid19-vaccine​ to learn more.

Third doses

For some people, 2 doses may not give enough protection. You may need a third dose to complete your primary series if you have a health problem that weakens your immune system. For example:

  • You've had or will have a an organ or stem cell transplant.
  • You have kidney disease and need dialysis.
  • You have acquired immunodeficiency syndrome (AIDS).
  • You take certain medicines that weaken your immune system.

Booster doses

After your primary series, you should have an extra (booster) dose for more protection if you are age 70 years or older. You should also have a booster dose if you are age 18 years or older and you:

  • live in a certain type of seniors’ facility, such as long-term care
  • are Indigenous
  • are a frontline healthcare worker who has in-person contact with patients and you had your first 2 doses of COVID-19 vaccine less than 8 weeks apart
  • had 2 doses of AstraZeneca/COVISHIELD vaccine or 1 dose of Janssen vaccine and you haven't had any doses of mRNA COVID-19 vaccine

Doses for travel

If you’re travelling outside of Canada and you’ve had only viral vector-based vaccines or different vaccines for your first 2 doses, you may be able to get additional doses. This is only if your destination requires you to have a certain COVID-19 vaccine series.​

Can I get a viral vector-based COVID-19 vaccine if I’m pregnant or breastfeeding?

Yes, you can get a viral vector-based COVID-19 vaccine if you’re pregnant or breastfeeding. But research shows that mRNA vaccines are the safest type of COVID-19 vaccines to get during pregnancy.

When you’re pregnant, you have a higher risk of getting very sick from COVID-19. Getting a COVID-19 vaccine when you’re pregnant lowers your risk of getting seriously ill from the virus.

If you’re pregnant or breastfeeding and have questions about getting a COVID-19 vaccine, talk to your healthcare provider.

Where can I get a COVID-19 vaccine?

Go to ahs.ca/covidvaccine to find out where and when you can get a COVID-19 vaccine.

Are there side effects from viral vector-based COVID-19 vaccines?

There can be side effects from viral vector-based COVID-19 vaccines, but they tend to be mild and go away in a few days. Side effects may include:

  • redness, warmth, swelling, bruising, itching, or feeling sore where you had the needle
  • feeling tired, unwell or have a headache
  • a fever or chills
  • body aches, sore joints, or pain in your legs or arms
  • feeling sick to your stomach (nausea), vomiting (throwing up), or loose stool (diarrhea)
  • a sore throat, cough, or runny nose

You may be more likely to have these side effects if you have another vaccine at the same time as a COVID-19 vaccine.

Current information shows that there’s a similar risk of side effects after a first, second, or additional dose of COVID-19 vaccine. Research continues to find out more about the risk of side effects after additional doses.

It’s important to stay at the clinic for 15 minutes after your vaccine. Some people may have a rare but serious allergic reaction called anaphylaxis. If anaphylaxis happens, you’ll get medicine to treat the symptoms.

It’s rare to have a serious side effect. Call Health Link at 811 to report any serious or unusual side effects.

What rare events have been reported after getting the AstraZeneca/COVISHIELD or the Janssen vaccines?

Research is still happening to learn more about the risk of rare events after getting the AstraZeneca/COVISHIELD or Janssen vaccines. It’s not yet known if having a history of certain health problems puts you at higher risk of rare events after having these vaccines.

Your risk of getting seriously ill from COVID-19 is much higher than your risk of having a rare event after these vaccines. Go to COVID-19 Vaccine Frequently Asked Questions for more information.

Blood clots, low platelets, bleeding

There have been very rare reports of blood clots, low levels of platelets (these help your blood to clot), and bleeding after getting either the AstraZeneca/COVISHIELD or the Janssen vaccines.

These events happened 4 to 28 days after getting the vaccine. The risk of these events after getting the AstraZeneca/COVISHIELD vaccine is about:

  • 1 in 55,000 after the first dose
  • 1 in 600,000 after the second dose

The risk of these events after getting the Janssen vaccine is about 3 in 1 million.

Talk to your healthcare provider if you have a condition that puts you at risk for blood clots or if you’ve ever had immune thrombocytopenia (ITP). ITP is when your immune system attacks the blood cells you need for normal blood clotting and causes bleeding.

If you have any of the following symptoms within 42 days of being immunized, get medical help right away:

  • trouble talking or moving a part of your body
  • shortness of breath
  • chest pain
  • severe swelling, pain, or a colour change in your arm or leg
  • stomach pain that doesn’t go away
  • a severe headache that doesn’t go away
  • blurry vision
  • seizures

Capillary leak syndrome

There have been very rare reports of capillary leak syndrome (CLS) within the first few days after getting the AstraZeneca/COVISHIELD or Janssen vaccines. In some reported cases, the person had a history of CLS. CLS is a serious condition that causes fluid to leak from the small blood vessels (capillaries). This causes sudden swelling of the arms and legs, sudden weight gain, and low blood pressure causing you to feel faint. CLS can cause death. Talk to your healthcare provider if you have any history of CLS. Get medical help right away if you have any of these symptoms.

Guillain-Barre syndrome

There have been very rare reports of Guillain-Barre syndrome (GBS) up to 42 days after getting the AstraZeneca/COVISHIELD or Janssen vaccines. GBS is a serious condition that causes pain or numbness, muscle weakness, and in severe cases, paralysis. Most people fully recover from GBS but some may continue to have symptoms. GBS can cause death. The risk of GBS after getting either AstraZeneca/COVISHIELD or Janssen vaccine is about 1 in 100,000. Get medical help right away if you have any of these symptoms.​

How can I manage side effects?

To help with soreness and swelling, put a cool, wet cloth over the area where you had the needle.

There is medicine to help with a fever or pain. Check with your doctor or pharmacist if you’re not sure what medicine or dose to take. Follow the directions on the package.

Some people with health problems, such as a weak immune system, must call their doctor if they get a fever. If you’ve been told to do this, call your doctor even if you think the fever is from the vaccine.

What vaccine will I get for my primary series?

You will get an mRNA COVID-19 vaccine for your primary series. But if you can’t get or don’t want this type of vaccine, you can get a viral vector-based vaccine if you’re age 18 years or older.

Usually you get the same vaccine for all your doses. But if you got the AstraZeneca/COVISHIELD vaccine as your first dose, you can choose the same vaccine or an mRNA vaccine for your next dose.

Whichever vaccine you get to complete your primary series protects you against COVID-19.

Go to ahs.ca/seconddose​ for more information.

What vaccine will I get for my booster or additional dose?

You will get an mRNA vaccine for any booster or additional doses. If you can’t get or don’t want an mRNA vaccine, you can get the AstraZeneca/COVISHIELD vaccine.

The Pfizer-BioNtech and Moderna vaccines are licensed for booster doses for people age 18 years or older who get their booster dose no sooner than 6 months after their second dose.

In other cases, the vaccine isn’t licensed for more than 2 doses. But vaccine experts support this in certain situations. This is called “off-label use.”

Getting more than 2 doses of a COVID-19 vaccine is off-label use if:

  • You are age 5 to 17 years.
  • You get a dose sooner than 6 months after your second dose.
  • You get the AstraZeneca/COVISHIELD vaccine as a third dose, booster dose, or additional dose.

If you’re getting more than 2 doses, talk to your healthcare provider about which vaccine you can get and when you should have your doses.

What if I had or am getting another type of vaccine?

You can get any vaccine at the same time as, any time before, or any time after a viral vector-based ​COVID-19 vaccine.

Who should not get a viral vector-based COVID-19 vaccine?

You may not be able to get a viral vector-based COVID-19 vaccine if you:

  • have an allergy to any part of the vaccine
  • had a severe (serious) or unusual side effect after this vaccine or one like it
  • have a history of capillary leak syndrome (CLS)
  • are under age 18 years

Check with your doctor or a public health nurse before you get a viral vector-based COVID-19 vaccine.

Be sure to talk to your doctor before you get a viral vector-based COVID-19 vaccine, if you:

  • have a weak immune system (because of a medicine you take or a health problem)
  • have an autoimmune disorder (like rheumatoid arthritis or lupus)
  • have a stem cell or organ transplant
  • have a history of immune thrombocytopenia (ITP)
  • are at higher risk of blood clots
  • have been treated for a COVID-19 infection in the last 90 days

Always tell your healthcare provider if you have allergies or if you've had a side effect from a vaccine in the past.

Facts about COVID-19

What is COVID-19?

COVID-19 is a new strain of coronavirus that’s caused a worldwide pandemic. The virus causes an infection in the lungs and airways and is a type of respiratory illness. Symptoms may include:

  • a fever
  • a cough
  • shortness of breath or trouble breathing
  • a sore throat
  • a runny or stuffy nose
  • loss of sense of smell or taste

Most people have only mild symptoms or no symptoms at all. But if you’re an older adult or have other health problems, you can get very sick and may need care in a hospital. In serious cases, COVID-19 can cause a type of lung infection called pneumonia. Pneumonia makes it hard to breathe without help and can even lead to death.

Go to COVID-19: How to manage symptoms​ for a list of all symptoms that may be related to COVID-19.

How does it spread?

COVID-19 spreads:

  • when an infected person sneezes, coughs, or talks
  • if you breathe in the virus
  • if you touch something that has the virus on it (like hands or a doorknob) then touch your eyes, mouth, or nose

It’s important to know that you and others can spread COVID-19 before symptoms start.

Go to ahs.ca/covid to find out more.

How can I prevent COVID-19 from spreading?

To prevent COVID-19 from spreading:

  • get immunized
  • wash your hands with warm water and soap or use an alcohol-based hand sanitizer often
  • don’t touch your face, nose, or mouth with unwashed hands
  • cover your cough or sneeze into your arm or a tissue, not your hand
  • stay home when you’re sick
  • avoid close contact with people who are sick

If you think you’ve had contact with COVID-19 or have symptoms, take the COVID-19 Self-Assessment at ahs.ca/testing.

More information

Current as of: November 24, 2021

Author: Provincial Immunization Program, Alberta Health Services