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COVID-19 vaccines and cancer

For people with cancer

This webpage will give you information about:

This webpage is meant to give you general information about what is known about the vaccines right now. 

Last updated: April 20, 2021. The webpage may change as we continue to receive new information.

Should I get the COVID-19 vaccine?

People with cancer may have a higher risk of:

  • Getting COVID-19
  • Getting very sick from COVID-19
  • Dying from COVID-19

For these reasons, most people with cancer should get the COVID-19 vaccine to protect themselves.

Health Canada has recently approved four COVID-19 vaccines from the companies:

  • Pfizer
  • Moderna
  • AstraZeneca
  • Johnson & Johnson (Janssen)

What groups of people with cancer are most at risk?

While any person with cancer may be at higher risk of getting very sick if they get COVID-19, the following groups are known to be at higher risk:

  • People with lung cancer or cancers of the blood like leukemia, lymphoma and multiple myeloma
  • People who were diagnosed with cancer in the last year
  • People with cancer who are 65 years or older
  • People who have had a stem cell transplant in the last six months
  • People getting treatments that weaken the immune system like chemotherapy and targeted therapies (for example, immunotherapy)

How do COVID-19 vaccines work?

Vaccines (also called immunizations or vaccinations) are used to help our immune system recognize and protect our body against certain infections.

Messenger RNA (mRNA) vaccines

The Pfizer and Moderna vaccines are messenger RNA (mRNA) vaccines.

  • The cells in our body make mRNA all the time. The cells use mRNA to make the proteins our bodies need to function.
  • COVID-19 mRNA vaccines teach our cells how to make a protein when the immune system finds the COVID-19 virus. The protein gets the immune system to start making antibodies (cells that fight infection). These antibodies protect us from the COVID-19 virus if it enters our body in the future.

Viral vector-based vaccines

The AstraZeneca and Johnson & Johnson vaccines are viral vector-based vaccines.

  • Viral vector-based vaccines use a harmless virus as a delivery service. The virus is not the virus that causes COVID-19.
  • The harmless virus carries genes from the spike protein (the outer layer that helps a virus stick to healthy cells) of the COVID-19 virus into the body. The immune system reacts to these genes and starts making antibodies to fight them. By doing this, the immune system learns how to make antibodies to protect us if the COVID-19 virus enters the body in the future.

Are the vaccines safe?

How do I know the vaccines are safe?

Health Canada makes sure that vaccines meet very strict safety and efficacy (how well something works) standards before they are approved for our use. The COVID-19 vaccines went through the same amount of safety checks as any other vaccine or medicine.

To read more about how the vaccines were approved for use, go to sunnybrook.ca/vaccine.

Can I get COVID-19 from taking the vaccine?

No, it is not possible to get COVID-19 from taking the vaccine. Vaccines for COVID-19 use a part of the virus (the spike protein) or a gene from the virus that cannot cause COVID-19.

Can I spread the virus to other people even after I get the vaccine?

Yes. The COVID-19 vaccine will reduce the chance of you getting really sick from the COVID-19. But the vaccine may not protect you from getting infected with the COVID-19 virus. This means that there is still a chance you could get COVID-19 but have no symptoms of the disease.

If you get COVID-19 you could spread the virus to other people without knowing it. At this time, people who get a vaccine need to continue to wear masks and practice physical distancing.

Is the vaccine safe for people with cancer?

Yes, the vaccine is safe for most people with cancer.

Some cancer treatments like chemotherapy, radiation or immunotherapy can affect the immune system. Some people getting cancer treatment may not get as much protection from the vaccine as other people. But any amount of protection will keep you safer than none.

It is unknown at this time if some people with cancer will need to get the vaccines again after they finish treatment. More studies are needed to know how well the vaccine works for people with cancer.

Chemotherapy »

People getting chemotherapy can get the COVID-19 vaccine. But because chemotherapy slows down or stops your immune response, this may reduce how well the vaccine works. Your cancer doctor may change your treatment so that the vaccine can work better.

Radiation therapy »

People getting radiation therapy can get the COVID-19 vaccine. Radiation therapy does not seem to affect how well the vaccine works. People getting radiation therapy can get the vaccine at any time before or during treatment.

Immunotherapy »

People getting immunotherapy (for example, checkpoint inhibitors) may be able to get the COVID-19 vaccine. If you get the vaccine, your health care team will need to watch you closely for any vaccine side effects.

Stem cell transplant or adoptive cell therapy »

People who are getting stem cell transplants or adoptive cell therapy may have a weakened immune system for a short amount of time. A weakened immune system may reduce how well the COVID-19 vaccine works.

You may have to wait until your immune system recovers after treatment before getting the vaccine. Some patients may also need to get the vaccine again at a later date.

Immunosuppressive therapy »

Whether people getting immunosuppressant therapy can get a COVID-19 vaccine depends on the type of therapy. If you are getting rituximab, it may reduce how well the vaccines work. Talk to your cancer doctor about when it is safe for you to get a COVID-19 vaccine.

Immunosuppressant therapy may reduce how well the vaccines work. If it is safe for you to get a vaccine, get a vaccine as soon as it is offered to you.

Can I still get the COVID-19 vaccine if I already had COVID-19?

Yes. People who have COVID-19 can get the vaccine after they recover from the virus. The vaccine trials included people who had been infected with COVID-19 and the vaccine was found to be safe.

Experts do not know how long antibodies last after someone has had COVID-19. The vaccine may help your body fight a future COVID-19 infection. 

Can I get the COVID-19 vaccine if I have symptoms of COVID-19?

If you have any symptoms of COVID-19, wait to get the vaccine. Talk to your health care team about your symptoms and getting a COVID-19 test.

Possible side effects from the vaccine

As with other vaccines, some people may get mild side effects in the days after. Most side effects will go away on their own.

Learn more about the possible side effects

The most common side effects from the mRNA vaccines are:

  • Fatigue (tiredness)
  • Headache
  • Muscle aches
  • Pain where you got the shot (on your upper arm)
  • Redness and swelling where you go the shot (on your upper arm)
  • Joint pain
  • Mild fever
  • Swollen glands (this happens less often)

If you get a vaccine that has two doses, these side effects are more likely to happen after the second dose. Speak to your health care team if these side effects last for more than three days.

Serious side effects from the vaccine are rare. If you get any of these side effects within three days of getting the vaccine, call your health care team right away or go to your nearest emergency department. These serious side effects include:

  • Hives (bumps on the skin that are often very itchy)
  • Swelling of the face or mouth
  • Trouble breathing
  • Very pale colour in your face or serious drowsiness (feeling very sleepy)
  • Very high fever (over 40°C)
  • Convulsions (spasm or shaking) or seizures (fit of uncontrolled movements)
  • Numbness or feeling of 'pins and needles'

If you have serious allergies or have had a serious allergic reaction to other vaccines, drugs or food, talk to your cancer doctor before you get the COVID-19 vaccine.

Should I be concerned if I have severe allergies?

Talk to your cancer doctor before you get a COVID-19 vaccine if you have serious allergies or had an anaphylaxis reaction (very serious allergic reaction that could cause you to stop breathing) to:

  • Other vaccines
  • Other medicines, including cancer medicines like chemotherapy
  • Any foods

If you have had a serious allergic reaction to any of the ingredients in any of the vaccines, talk to your doctor about your options. If you are allergic to an ingredient in one company’s vaccine you may be able to get a different vaccine.

For a complete list of ingredients in the four approved vaccines, visit covid-19.ontario.ca/covid-19-vaccines-ontario

How well do the vaccines work?

COVID-19 vaccines work well to protect people from:

  • Getting very sick from COVID
  • Needing hospital treatment if they get COVID-19
  • Dying from COVID-19

Is one company’s vaccine better than another?

The best vaccine is the first one you can get.

  • You may have heard or read about the efficacy rates for each vaccine. A vaccine’s efficacy rate refers to how well the vaccine did in clinical trials under ideal conditions.
  • The conditions for each COVID-19 vaccine clinical trial were different and cannot be compared to each other. The clinical trials were set up differently, measured different things and run during different times of the pandemic.
  • For example, each clinical trial had a different definition for what counted as COVID-19 infection.
    • Some clinical trials counted one mild symptom as a COVID-19 infection while others counted two mild symptoms or one moderate symptom.
    • Some clinical trials counted COVID-19 symptoms one week after the second dose while others counted symptoms two weeks after the second dose.

All the COVID-19 vaccines protect you equally against getting very sick if you get COVID-19.

How long will protection from the vaccine last?

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

How will I get the vaccine?

COVID-19 vaccines are given in the upper arm muscle just like a flu shot.

  • The Pfizer, Moderna and AstraZeneca vaccines are given in two doses.
  • The Johnson & Johnson vaccine is given in one dose.

How soon do the vaccines start to work?

It takes time for your body to build up an immune response to protect you.

  • If you get a vaccine that needs two doses (like Pfizer, Moderna, or AstraZeneca), you will have some protection after the first dose. You need a second dose for full protection.
  • If you get the Johnson & Johnson vaccine, it takes at least two weeks for the vaccine to protect you from getting very sick from COVID-19.

When will I get the COVID-19 vaccine?

We are following the Government of Ontario’s direction for the rollout of the COVID-19 vaccine. You may be able to get your COVID-19 vaccine at a pharmacy or hospital close to you. 

To learn more, go to:

Do I still have to wear a mask and practice physical distancing after I get the vaccine?

Yes. You still need to wear masks and practice physical distancing until a large number of people get the vaccine. It is also unknown at this time whether the vaccine provides long-term protection from COVID-19.

Other vaccine information

Can I still get a flu shot if I have not had one yet?

Yes. The flu and the COVID-19 virus are not the same thing. For people with cancer and weakened immune systems, the flu can be serious and sometimes life-threatening (cause death).

  • People with cancer should get a flu shot that has an inactive (dead) flu virus. Most flu shots do not contain the live virus.
  • Do not get the flu vaccine through the nose as nasal spray. These nasal sprays contain live flu virus. People with cancer and those in the same household, should not get the nasal spray flu vaccine.

Your health care team will tell you when to get the flu shot depending on your cancer type and treatment.

Can I still get a flu shot if I have COVID-19?

If you have COVID-19 or think you may have the virus, wait to get your flu shot. This keeps other people safe from being exposed to COVID-19.

Can I get other vaccines at the same time I get the COVID-19 vaccine?

No. You should not get other vaccines at the same time you get the COVID-19 vaccine. Do not get other vaccines until at least 28 days after you get the second dose of the COVID-19 vaccine.

If you get a vaccine before the COVID-19 vaccine, wait 14 days before you get the COVID-19 vaccine.

For more information

Please go to the Ontario Ministry of Health’s website for more information.

The information above has been adapted from “Covid-19 Vaccines and Cancer” (2021), with permission from Cancer Education, UHN Patient Education.