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COVID-19: Get the latest updates or take a self-assessment.

What you need to know about COVID-19 vaccines: Information for people with cancer

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Read this information to learn about:

  • Why people with cancer should get vaccinated
  • How the vaccines work and how they are given
  • Possible side effects from the vaccine
  • Why it is important to follow public health rules after getting the vaccine

This information is meant to give you, your family and caregivers general information about the COVID-19 vaccines and what is known now.  

Why should people with cancer get vaccinated?

People with cancer may have a higher risk of:

  • Getting COVID-191
  • Getting very sick from COVID-192
  • Dying from COVID-191,2,3,4,5,6,7

The government is rolling out a 3-phase plan to vaccinate people in Ontario. People with cancer can get the vaccine in Phase 2 of the plan.8 People with cancer should get the COVID-19 vaccine as soon as they are able.

The sooner that most people in Ontario get vaccinated, the sooner life can go back to normal.

Check the websites of Ontario’s Ministry of Health and your local public health agency to find out more details. Call the Ontario Vaccine Information Line (1-888-999-6488) if you prefer to use the phone.

What groups of people with cancer are most at risk?

The following groups of people with cancer have an even higher risk of getting very sick from COVID-19. Those who:

  • Are 65 years or older9
  • Have had a stem cell transplant in the last 6 months10
  • Are getting or have recently stopped having cancer treatments11
  • Have been diagnosed with cancer in the last year1
  • Have cancers of the blood like leukemia, lymphoma and multiple myeloma3,12,13,14
  • Have lung cancer3,12,13,14
  • Have cancer that has spread to another area of the body (metastatic cancer)2
  • Have had cancer surgery within the last 2 months2,15

If you are in one of the above groups, you must be extra careful to protect yourself from getting COVID-19. Stay home as much as possible, stay apart from people you do not live with, wear a mask and wash your hands often.

How do the COVID-19 vaccines work?16

There are 4 vaccines approved for use in Canada.

The COVID-19 vaccines from Pfizer and Moderna are messenger RNA (mRNA) vaccines. mRNA is type of molecule (small part of a cell) that our bodies are always making. mRNA vaccines teach our bodies to make proteins that tell our immune systems to fight the COVID-19 virus.

The COVID-19 vaccines from AstraZeneca (may also be called Covishield) and Janssen (Johnson & Johnson) are viral vector-based vaccines. This type of vaccine uses another harmless virus (not COVID-19) to teach your body to build up immunity to COVID-19 without making you sick. The flu shot is also a viral vector-based vaccine.

You cannot get COVID-19 from either type of vaccine.

When is the best time to get a vaccine?

You should get a vaccine as soon as you are able.

If you are getting any of the treatments below, speak to your cancer care team about when it is best to get the vaccine during your treatment:

  • Chemotherapy
  • Immunotherapy
  • Stem cell transplant
  • Adoptive cell therapy
  • Immunosuppressive therapy (treatments that weaken your immune system)

Which vaccine will I get?

The vaccine you get will depend on which vaccine is available in your area at the time of your appointment, your age and other factors. Check with your local public health unit and the Ontario Ministry of Health’s website to learn about which vaccine you will get.

The best vaccine for you is the first one you are offered.

How do I know that the vaccines are safe?

Health Canada has one of the most careful review processes in the world. They make sure that all vaccines meet very strict safety and efficacy (how well something works) standards before they are approved for use.16

The COVID-19 vaccines are safe for people with cancer.17,18,19 It is important that people with cancer get vaccinated because they may be at a higher risk for more severe outcomes of COVID-19.

The vaccines:

  • Were tested on thousands of people16
  • Have met all the requirements for approval, including safety16
  • Will be observed for any issues as they are used across the world16

How are the vaccines given?

The COVID-19 vaccines are given as shots (needles) into the upper arm, like a flu shot.

The Pfizer, Moderna, AstraZeneca and Covishield vaccines are 2 shots. The Janssen (Johnson & Johnson) vaccine is 1 shot.

For 2-shot vaccines, the second shot will be given weeks or months after the first shot. When booking your vaccine appointment, ask about the timing of your second shot to make sure it follows the advice of your cancer care team.

How well do the vaccines work?

All the vaccines have been shown to work well in large clinical trials (a research study that involves humans). The vaccines have shown that they protect people from getting very sick, needing to be hospitalized and dying from COVID-19.

People with weakened immune systems, including some people with cancer, may not get as much protection from the vaccine as others.20,21,22 The vaccines are still being studied for how well they work on the virus variants.

How soon does the vaccine start to work and how long does it last?23,24,25,26,27,28,29

For the 2-shot vaccines, you will begin to get some protection about 2 weeks after the first shot. For the 2-shot vaccines you need the second dose to get the most protection. If you skip the second dose, the vaccine will not work as well to protect you.

For the single shot vaccine, you will begin to get some protection 2 weeks after the single shot.

At this time, we do not know how long protection from the vaccine will last. Since the vaccines are new, they will need to be studied over time to see how long they will work.

What are possible side effects from the vaccines?

Some people may have mild side effects in the days after their shot. Most side effects will go away on their own. For 2-shot vaccines, side effects may be worse after the second shot.

The most common side effects from the vaccines are:16,24,26,27,28,30,31,32

  • Pain, redness or swelling in your arm where the needle was given
  • Fatigue (tiredness)
  • Headache
  • Body chills
  • Muscle aches
  • Joint pain
  • Mild fever
  • Diarrhea
  • Vomiting
  • Swollen glands can happen for a few days after getting a COVID-19 vaccine. Talk to your cancer care team if this lasts for more than a few days.

If side effects last for more than 2-3 days, make sure you speak to your health care team.24,26,33,34,35

After you get the COVID-19 vaccine, wait for at least 15 minutes before going home. This wait is to check for side effects or an allergic reaction.

Rare but serious side effects

A rare but serious form of blood clots has been linked to the AstraZeneca vaccine.36 These are a different type of clot than those that can be caused by cancer and cancer treatments. The blood clots have mostly happened in women under the age of 55. The blood clots have happened 4-20 days after the vaccine is given.28,37,38,39,36

Can the vaccine cause allergic reactions?

It is possible to be allergic to ingredients in the COVID-19 vaccines.40,41,42 If you have serious allergies or have had a serious allergic reaction to other vaccines, drugs, or food, talk to your cancer care team or your family health team before you get the COVID-19 vaccine.

You may need to speak to an allergy doctor to see if it is safe for you to get the vaccine. You may also need to get your vaccine in a hospital instead of at a clinic or pharmacy. For more information about ingredients in the vaccines search the vaccine names on the Health Canada website or ask your health care team.

Do I need to keep following public health rules after getting the vaccine?

Yes. After getting the vaccine it is important to keep following public health rules including:

  • Keep wearing a mask
  • Wash your hands often
  • Stay apart from people that you do not live with

You must keep following public health measures because:

  • It takes time for your body to build up protection after getting the vaccine
  • It is possible for COVID-19 to spread even between people who have already gotten the vaccine
  • We need to control the spread of COVID-19 in our communities until everyone has had a vaccine

Are there times when I should wait to get the vaccine?

There are times when some people should wait to get the COVID-19 vaccine.

If you have COVID-19 you should wait to get the vaccine until after you recover from the virus. You need to get the vaccine even if you have already had COVID-19 because it is possible to get the virus again. Talk to your health care team about when you should get the vaccine after you recover.

If you have symptoms of COVID-19 or are currently self-isolating you should wait to get the vaccine. Talk to your health care team about your symptoms and getting a COVID-19 test. Your health care team will tell you when to get the vaccine.

If you need to get another type of vaccine (such as the flu shot) wait for at least 28 days after getting your COVID-19 vaccine (single dose or 2nd dose of a 2-shot vaccine) before getting any other vaccines.43,44

If you have already gotten another type of vaccine, wait 14 days before you get the COVID-19 vaccine.43

Schedule your vaccine at least one week before or one week after getting surgery. This is so that any vaccine side effects are not mistaken for problems after surgery.45

How did research teams develop the vaccines so quickly?

Some reasons research teams were able to develop the COVID-19 vaccines so quickly are:

  • The COVID-19 virus is similar to other viruses. Researchers already knew a lot about these types of viruses.
  • Research teams around the world started to work on the vaccine right away when the COVID-19 virus was found
  • Research teams all over the world shared information with each other
  • Many people quickly signed up for clinical trials (a research study that involves humans) to test the vaccines. For example, over 200,000 people in Britain took part in clinical trials.

For more information

Talk to your health care team for more information about the COVID-19 vaccines.

Health Canada

Ontario Ministry of Health

Public Health Unit locator

Ontario Government Ethical Framework for COVID-19 Vaccine Distribution


Provincial Vaccine Information Line

Call if you have questions about Ontario's COVID-19 vaccination program or booking your vaccination appointment. Information is available in multiple languages.

Telephone: 1-888-999-6488

TTY: 1-866-797-0007


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