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FAQ for Medical Conditions

Your specialists from St. Michael’s Hospital Department of Medicine have prepared some information to answer questions about the safety of the Pfizer-BioNTech and Moderna COVID-19 vaccines. Read the information below to learn about recommendations for people with specific health conditions. These recommendations are consistent with those from national societies for these conditions.

We will update this page if we get new information that affects our recommendations.

  • People with suppressed immune systems (immunosuppression). This can be due to disease or treatment. It includes:
    • People having chemotherapy
    • People having radical radiotherapy
    • Transplant recipients (including solid organ, bone marrow or stem cell recipients)
    • People with HIV infection at all stages
    • People with multiple myeloma or genetic disorders affecting the immune system (for example IRAK-4, NEMO, complement disorder, SCID).
  • Patients having immunosuppressive or immunomodulating biological therapy. This includes, but is not limited to:
    • Patients getting anti-TNF, alemtuzumab, ofatumumab, rituximab or obinotuzumab therapy
    • Patients taking protein kinase inhibitors or PARP inhibitors
    • Patients treated with steroid sparing agents such as cyclophosphamide and mycophenolate mofetil
    • Patients having stem cell therapy, CAR-T therapy, chemotherapy, immune checkpoint inhibitors and CD4/6 inhibitors.
  • People treated with or likely to be treated with systemic steroids for more than a month at certain doses – talk to your doctor to see if this applies to you
  • Anyone who may need long term treatments to suppress their immune systems, including people with:
    • Cancers of the blood, bone marrow and lymph nodes (leukaemia, lymphoma, and myeloma)
    • Systemic lupus erythematosus
    • Rheumatoid arthritis and psoriasis

See “Immunocompromised or taking medicines that suppress your immune system” for more information.

  • There is a very low risk of allergic reactions to the Pfizer-BioNTech and Moderna vaccines. They are safe for the vast majority of people.
  • If you have allergies that are not related to the vaccine (for example to foods, pets, drugs, insect venom, latex and environmental allergies), you can have the vaccine. You don’t need to take any special precautions.
  • If you are allergic to any vaccine ingredients, especially polyethylene glycol (PEG) and polysorbate, talk to your doctor before getting the vaccine.
  • If you are allergic to chlorhexidine, tell the staff at the vaccine clinic before you get the vaccine.
  • There is no natural rubber latex in the vial stoppers for the Pfizer-BioNTech and Moderna vaccines.
  • The vaccines do not contain egg or gelatin.

What should I do if I had an allergic reaction right after getting my first Pfizer-BioNTech or Moderna vaccine?

  • Do not get another vaccine until you get an evaluation by an allergist-immunologist.
  • The allergist-immunologist may decide it is safe to get another vaccine with certain precautions. They will give you a document with special instructions. You must bring this document to get a vaccine.

What if I had a severe allergic reaction (anaphylaxis) to another vaccine or injectable therapy?

  • You must be evaluated by an allergist-immunologist before getting a COVID-19 vaccine.

  • Currently, there is little evidence that people with an autoimmune condition (including rheumatoid arthritis, lupus, vasculitis) are at increased risk of severe COVID-19
  • Talk to your doctor about the risks and benefits in your situation, including:
    • The risks and benefits of the vaccine
    • Your risk of getting COVID-19
    • Risks to your health if you are infected
    • Your degree of autoimmunity and how this may affect how well the vaccine works
    • Understanding that we don’t have enough information about COVID vaccines for people with autoimmune conditions
  • If you and your doctor agree, you can get the vaccine. This applies to you if you are getting stem cell therapy, CAR-T therapy, chemotherapy, immune checkpoint inhibitors, monoclonal antibodies (eg rituximab), and other targeted agents (eg CD4/6 inhibitors, PARP inhibitors).

  • The COVID-19 vaccines approved in Canada are safe for people with bleeding disorders.
  • Before you go to the vaccine clinic:
    • If you are on prophylaxis with factor concentrate, you should time your prophylaxis with the day of your vaccine injection.
    • If you treat on-demand but have a history of severe bleeding, you may need a treatment with factor concentrate before the vaccine injection. Please contact your bleeding disorder team.
  • When you go to the vaccine clinic:
    • Tell staff you have a bleeding disorder before you get the vaccine.
    • Ask them to use a smaller gauge needle, if possible, and to apply 10 minutes of pressure after the injection.
  • You will still be eligible for future hemophilia gene therapy if you get the COVID-19 vaccine.
  • If you have Hereditary Hemorrhagic Telangiectasia (HHT), you do not have an increased risk of bleeding at the injection site. (See the respiratory diseases section for more information about COVID risk and vaccines for people with HHT).
  • If you have a history of severe allergic reactions to medicines containing polyethylene glycol (PEG) or polysorbate (e.g. Adynovate, Jivi, Rebinyn), talk to your health care provider to decide which vaccine is best for you.
  • If you take immune suppressive medicines (e.g. rituximab, obinotuzumab, corticosteroids), you can have the vaccine, but these medicines may make the vaccine less effective.
  • If you are getting immune tolerance induction therapy, this should not interfere with vaccine effectiveness.

  • The information below is for people taking the following medicines:
    • Warfarin
    • A newer blood thinner: apixaban (Eliquis), dabigatran (Pradaxa), edoxaban (Lixiana), or rivaroxaban (Xarelto)
    • Aspirin or a similar drug like clopidogrel (Plavix) or ticagrelor (Brillinta) – because of a previous heart attack or stroke
  • We encourage you to get an available COVID-19 vaccine
  • There is a small risk of bruising at the vaccination injection site. However, we do not expect any serious effects related to being on blood thinning treatment.
  • To reduce bruising, we suggest applying pressure to the vaccine injection site for 3 to 5 minutes after injection.

  • The Pfizer-BioNtech and Moderna vaccines do not contain live or whole virus, and cannot cause COVID infections.
  • Talk to your cancer health care team to discuss the risks of getting COVID-19 and the risks and benefits of the COVID vaccine. You can get either the Pfizer-BioNTech or Moderna vaccine if you and your care team agree.
  • Please note that your immune system may not respond as strongly to the vaccine if you are immunocompromised or are getting immunosuppressant therapy. This means you may not have as much protection from the virus as others who get the vaccine. Continue to follow Public Health guidance to avoid exposure, unless your health care team tells you differently.

  • We recommend that people with diabetes and other endocrine conditions get a COVID vaccine, including people with an autoimmune basis for their condition (unless there is another reason you should not get the vaccine)
  • If you have adrenal insufficiency, you should double your usual dose for 2 days after getting the vaccine.

  • We recommend that people with heart conditions get the COVID-19 vaccine. This includes if you have coronary artery disease, heart attack, heart failure or cardiomyopathy.
  • Patients with heart conditions have a higher risk of complications from COVID-19 if they get the disease. The COVID-19 vaccines approved in Canada have been shown to be safe and effective for the vast majority of patients with heart conditions.
  • Heart transplant patients should read the section on ‘Immunocompromised or taking medicines that suppress your immune system’.

  • Clinical trials for the mRNA COVID-19 vaccines included people with stable HIV infection. There were no safety concerns for these people in the clinical trials.
  • All HIV patients can be offered the Pfizer-BioNTech or Moderna vaccines after counselling about the risks and benefits. The risks may vary depending on your condition:
    • The vaccine likely won’t increase your risk if you are receiving antiretroviral therapy, have an undetectable viral load and a CD4 count above 200 cells/microlitre
    • The risk is less clear among those with a detectable viral load or a CD4 count below 200 cells/microlitre.
  • People living with HIV (PLWH) who receive the Pfizer-BioNTech or Moderna vaccines are expected to have similar vaccine responses to people without HIV. However, the vaccine may not be so effective if you are immune compromised. We expect more studies looking at this issue.
  • We soon expect to learn more about how other COVID-19 vaccines work for people living with HIV.
  • For more information, see:

  • COVID-19 is a serious risk for you. You are more likely to have serious symptoms with COVID-19. This applies to you if you are having chemotherapy, have an organ transplant, take anti-rejection drugs or have immunodeficiencies.
  • If you have a primary immunodeficiency or acquired immunodeficiency (such as stable HIV infection) or you are on immunosuppressive medicines (such as after transplant), consider getting a COVID vaccine, unless your doctor recommends against it.
  • Both the Pfizer-BioNTech and Moderna vaccines can be safely taken by people who are immunocompromised. These are mRNA vaccines that do NOT contain live virus.
  • You may have a lower immune response to the vaccine. This means the vaccine may not work as well for you.

What if I have a primary immunodeficiency?

  • The vaccines currently approved for use in Canada have not been studied in patients with primary immunodeficiency.
  • You may not respond enough to the vaccine to be protected. More information may become available in the future. As we learn more, we can give more specific recommendations.
  • If you are on immunoglobulin replacement, you may get some protection against COVID-19 in the future, from antibodies in the immunoglobulin.
  • You can still get a COVID vaccine, unless your doctor recommends against it.

  • Both the Pfizer-BioNTech and Moderna COVID vaccines can be safely taken by people who have inflammatory bowel disease. These are mRNA vaccines that do NOT contain live virus.
  • If you have inflammatory bowel disease, you may be taking immune suppressant or biologic medicines, including infliximab (Remicade, Inflectra, Renflexis), adalimumab (Humira), vedolizumab (Entyvio), ustekinumab (Stelara), or golimumab (Simponi).
  • The Canadian Association of Gastroenterology recommends getting the COVID vaccine if you:
    • Have Crohn’s disease or ulcerative colitis
    • Have these conditions and are also taking immunosuppressant therapies or biologic medicines
  • We do not know whether taking immune suppressants or biologics will affect your immune response to the vaccine (how well it works for you). However, we do not recommend changing the timing when you take your medicines. Take your medicines at the usual time and dose.

  • COVID-19 is a serious risk for you. The anti-rejection medicines you take weaken your immune system. This means you are immunocompromised.
  • Transplant recipients have a higher rate of being hospitalized due to COVID-19. They also have mortality rates higher than 20% – about 2 out of every 10 kidney transplant patients who get COVID-19 will die from the disease.
  • Transplant patients are recommended to get a number of non-live vaccines. Studies show that transplant patients have a good immune response to these other vaccines.
  • All transplant societies including the Canadian Transplant Society strongly recommend getting vaccinated against COVID.

  • People living with liver disease are strongly encouraged to get vaccinated against COVID-19. This includes:
    • People with hepatitis B, hepatitis C, fatty liver, PBC, PSC, AIH, cirrhosis and other chronic liver diseases
    • People waiting for liver transplant
    • People who already received a liver transplant
  • Having liver disease does not increase the risk of having side effects from the vaccine
  • The medicines you take for liver disease, including any immunosuppressant medicines, are not a reason to decline a vaccine.
  • We do not know if the medicines you take for liver disease (including immunosuppressants) will affect how well it works for you. However, we still recommend getting the vaccine and taking your medicines on your usual schedule.

  • Your hematologist or immunologist thinks you should get the COVID-19 vaccine. This includes if you have systemic mastocytosis, mast cell activation syndrome or hereditary alpha tryptasemia.
  • There is not enough data on any of the COVID-19 vaccines to be certain about the risks in people with mast cell disease.
  • Based on what we know about COVID-19 and other vaccines, we think the benefits of the vaccine outweigh the risks for you.
  • There are special steps to follow before getting the vaccine.  Contact your hematologist or immunologist for further information.

  • We recommend for everyone with MS or other neuroimmunological disorders to get a COVID-19 vaccine. The risks of COVID-19 infection outweigh the potential risks of the vaccine.
  • The Pfizer/BioNtech and Moderna vaccines do not contain live virus and will not cause COVID-19 infection.  We have no reason to believe these COVID-19 vaccines will be dangerous for people with MS, including those on immunosuppressive drugs.
  • It is unlikely that these vaccines will make your MS worse,  provoke a relapse, or prevent disease modifying therapies (DMTs) from being effective.
  • It is important to continue your disease modifying therapy (DMT) unless your MS healthcare provider advises you to stop or delay it. Stopping some DMTs abruptly can cause your MS to worsen. In general, it is best to continue your MS treatment as usual, even if this causes you to have a lower response to the vaccine. Even a reduced response is better than none.  You should still get vaccinated when eligible – even if on these therapies.

  • The currently available COVID-19 vaccines are safe for people with respiratory disorders (including COPD, emphysema and chronic bronchitis), HHT and tuberculosis. We recommend these groups get a vaccine.
  • People with lung disease, HHT or TB should continue their therapies. Do not change your therapy without speaking with a doctor.

Respiratory disorders

  • COPD, emphysema, chronic bronchitis or pulmonary hypertension are known to increase the risk of severe illness from COVID-19.
  • Other chronic lung diseases such as severe asthma, idiopathic pulmonary fibrosis and cystic fibrosis, might increase the risk of severe illness from COVID-19.

Hereditary hemorrhagic telangiectasia (HHT)

  • Having HHT alone does not increase your risk for severe illness from COVID-19. However, if you have HHT and another condition or disease, your risk maybe increased. This includes if you have heart failure, pulmonary arterial hypertension and pulmonary arteriovenous malformation with hypoxemia.
  • People with HHT who get frequent iron infusions, blood transfusions or bevacizumab treatments may also have an increased risk of severe illness from COVID-19.

Tuberculosis (TB)

  • People with both TB and COVID-19 may have poorer treatment outcomes, especially if TB treatment is interrupted.
  • It is safe to receive the COVID vaccine when on TB medicines. If you have trouble tolerating your TB treatment, talk to your doctor about the best timing for your COVID-19 vaccine. This will help separate the side effects you may have from your TB medicine from any potential side effects you may have from the vaccine.

  • We recommend that people with rheumatologic diseases get the COVD-19 vaccine. This includes if you have rheumatoid arthritis, systemic lupus erythematosus (SLE), psoriatic arthritis, vasculitis or spondyloarthritis.
  • If you are taking medicine for your rheumatologic condition, it is important to continue your disease modifying therapy (DMT) unless your rheumatologist has told you to delay it around the time of vaccination
  • We do not recommend stopping your DMT completely before you get your vaccine. If you do, you may get a flare, and this would outweigh the benefits of the vaccine. Even a reduced response to vaccination is better than none. You should still get a vaccine when eligible, even if you are taking a DMT.

The information above is based on national society recommendations for the listed health conditions.

Last updated May 26, 2021