- Medical exemption updates regarding myocarditis and pericarditis based on updated NACI statement This guidance provides basic information only.# Background
This document is intended to assist physicians/specialists and nurse practitioners in evaluating contraindications or precautions to COVID-19 vaccination that may warrant a medical exemption. A contraindication is a situation where a vaccine should not be given as the risks outweigh any potential therapeutic benefit. A precaution is a condition that may increase the risk of an adverse event following immunization (AEFI) or compromise the ability of the vaccine to produce an immune response, which may result in deferral of immunization; however, there may be circumstances where the benefits of vaccination outweigh the potential risks from vaccination associated with the condition or where reduced immunogenicity still benefits immunocompromised individuals (Canadian Immunization Guide). In general, there are very few actual contraindications to Health Canada authorized COVID-19 vaccines that would qualify as medical exemptions and most individuals can receive COVID-19 vaccines. Only individuals with contraindications to mRNA and viral vector vaccines qualify for medical exemption. This document is based on recommendations from Canada's National Advisory Committee on Immunization (NACI) and expert clinician advice, prepared in consultation with Public Health Ontario and several specialist physicians with expertise in AEFIs.
As the context and evidence on COVID-19 vaccines evolves, this guidance will be updated and individuals with medical exemptions should be periodically re-evaluated by their nurse practitioner/physician/specialist as emerging evidence and new vaccine products become available.

# Reasons for Medical Exemption
Individuals who have experienced serious adverse events following COVID-19 immunization and those with certain medical conditions that may affect their immune response to immunization should be referred to an appropriate physician or nurse practitioner based on their adverse event/medical condition for further assessment. This should include a detailed patient history, assessment of the adverse event/medical condition and investigations/diagnosis, individualized riskbenefit analysis, and recommendations/options for future immunization. For serious or rare AEFIs, individuals should be thoroughly investigated to determine if the event can be attributed to an alternative etiology. Referral and specialist consultation support for physicians and nurse practitioners is available through Ontario's eConsult Service, OTN Hub, and the Special Immunization Clinic (SIC) Network. In many instances, safe administration of subsequent doses of COVID-19 vaccine is possible under the management of an appropriate physician or nurse practitioner. True medical exemptions are expected to be infrequent and should be supported by expert consultation.
Tables 1-4: Summary of conditions and/or adverse events following immunization (AEFI) that may qualify for a medical exemption to COVID-19 vaccination 1 As per NACI if the diagnosis with myocarditis is remote and they are no longer followed clinically by a medical professional for cardiac issues, they should receive an mRNA COVID-19 vaccine.

# Condition/AEFI Management
Myocarditis prior to initiating an mRNA COVID-19 vaccine series 

# Contraindications to Initiating an AstraZeneca or Janssen COVID-19

# Vaccine Series Condition/AEFI Management
History of capillary leak syndrome (CLS)
- Series should be completed with an mRNA vaccine.
- Qualifies for medical exemption if:
- Individual has medical exemption to completing their vaccine series with an mRNA vaccine.

# History of cerebral venous sinus thrombosis (CVST) with thrombocytopenia
- Series should be completed with an mRNA vaccine.
- Qualifies for medical exemption if:
- Individual has medical exemption to completing their vaccine series with an mRNA vaccine.

# History of heparin-induced thrombocytopenia (HIT)
- Series should be completed with an mRNA vaccine.
- Qualifies for medical exemption if:
- Individual has medical exemption to completing their vaccine series with an mRNA vaccine.

# History of major venous and/or arterial thrombosis with thrombocytopenia
- Series should be completed with an mRNA vaccine.
- Qualifies for medical exemption if:
- Individual has medical exemption to completing their vaccine series with an mRNA vaccine. 

# Adverse Events

# Other Condition/AEFI Management
Actively receiving monoclonal antibody therapy OR convalescent plasma therapy for the treatment or prevention of COVID-19
- Qualifies for time-limited medical exemption while they are actively receiving therapy. 

# History of Myocarditis prior to initiating an mRNA COVID-19 vaccine series
Individuals who have a history of myocarditis unrelated to mRNA COVID-19 vaccination should consult their clinical team for individual considerations and recommendations. Individuals previously diagnosed with myocarditis, whose diagnosis is considered remote and are no longer followed clinically by a medical professional for cardiac issues should receive the vaccine. This guidance is issued by the National Advisory Committee on Immunization (NACI). A medical exemption may be issued only if discussion has occurred with an appropriate physician or nurse practitioner regarding potential options for immunization with an mRNA COVID-19 vaccine or alternative, and the physician or nurse practitioner has determined that the individual cannot receive any COVID-19 vaccine.

# History of severe allergic reaction or anaphylaxis to any component of a COVID-19 vaccine
Individuals with a confirmed severe, immediate (4h following exposure) allergy (e.g., anaphylaxis) to a component of a specific COVID-19 vaccine or its container (e.g., PEG), are recommended to consult with an appropriate physician or nurse practitioner before receiving the specific COVID-19 vaccine. Individuals who are allergic to tromethamine (found in the Moderna COVID-19 vaccine and pediatric Pfizer-BioNTech COVID-19 vaccine) should be offered the Pfizer-BioNTech COVID-19 vaccine if 12 years or age or older, which does not contain this excipient. Individuals who are allergic to polysorbates (found in viral vector vaccines), should be offered an mRNA vaccine. A medical exemption may be issued only if discussion has occurred with the appropriate physician or nurse practitioner on options for immunization with the COVID-19 vaccine, including a risk-benefit analysis for the individual, and the physician or nurse practitioner has determined that the individual cannot receive any COVID-19 vaccine.
For a comprehensive list of components in the vaccine and packaging, please consult the product leaflet or information contained within the product monograph available through Health Canada's Drug Product Database.

# Contraindications to Initiating an AstraZeneca or Janssen COVID-19
Vaccine Series

# History of capillary leak syndrome (CLS)
Individuals who have experienced episodes of capillary leak syndrome (CLS) should not receive the AstraZeneca or Janssen COVID-19 vaccine. Very rare cases of capillary leak syndrome (CLS) have been reported following immunization with the AstraZeneca COVID-19 vaccine. This is a contraindication to receiving the AstraZeneca or Janssen COVID-19 vaccine. An authorized COVID-19 vaccine using a different platform (i.e., mRNA) should be offered for immunization. A medical exemption may be issued only if an mRNA COVID-19 vaccine is contraindicated for the individual.

# History of cerebral venous sinus thrombosis (CVST) with thrombocytopenia
Individuals who have experienced a previous CVST with thrombocytopenia should not receive the AstraZeneca or Janssen COVID-19 vaccine. This is a contraindication to receiving the AstraZeneca or Janssen COVID-19 vaccine. An authorized COVID-19 vaccine using a different platform (i.e., mRNA) should be offered for immunization. A medical exemption may be issued only if an mRNA COVID-19 vaccine is contraindicated for the individual.

# History of heparin-induced thrombocytopenia (HIT)
Individuals who have experienced a HIT should not receive the AstraZeneca or Janssen COVID-19 vaccine. This is a contraindication to receiving the AstraZeneca or Janssen COVID-19 vaccine. An authorized COVID-19 vaccine using a different platform (i.e., mRNA) should be offered for immunization. A medical exemption may be issued only if mRNA COVID-19 vaccine is contraindicated for the individual.

# History of major venous and/or arterial thrombosis with thrombocytopenia following any vaccine
Individuals who have experienced major venous and/or arterial thrombosis with thrombocytopenia following vaccination with any vaccine should not receive the AstraZeneca or Janssen COVID-19 vaccine. This is a contraindication based on recommendations issued by Ontario's Vaccine Clinical Advisory Group on Immunization. An authorized COVID-19 vaccine using a different platform (i.e., mRNA) should be offered for immunization. A medical exemption may be issued only if an mRNA COVID-19 vaccine is contraindicated for the individual.

# Adverse Events Following Immunization (AEFI) with COVID-19 vaccine Thrombosis with thrombocytopenia syndrome (TTS)/VITT following AstraZeneca or Janssen COVID-19 vaccine
Individuals who have experienced a major venous or arterial thrombosis with thrombocytopenia following vaccination with AstraZeneca or Janssen COVID-19 vaccine are contraindicated to receiving the AstraZeneca or Janssen vaccine. An authorized COVID-19 vaccine using a different platform (i.e. mRNA) should be offered for subsequent immunization. A medical exemption may be issued only if they have a medical exemption to completing their series with an mRNA COVID-19 vaccine.

# Myocarditis/Pericarditis following mRNA COVID-19 vaccination
A medical exemption may be issued if myocarditis/pericarditis was diagnosed after medical evaluation (e.g., ER physician, relevant specialist). In most circumstances, and as a precautionary measure until more information is available, individuals with a diagnosed episode of myocarditis/pericarditis within 6 weeks of receipt of a previous dose of an mRNA COVID-19 vaccine should defer further doses of the vaccine. This includes any person who had an abnormal cardiac investigation including electrocardiogram (ECG), elevated troponins, echocardiogram or cardiac MRI after a dose of an mRNA vaccine. This is a precaution based on recommendations issued by the National Advisory Committee on Immunization (NACI). NACI, Public Health Ontario (PHO), and the Ontario Ministry of Health (MOH) are following this closely and will update this recommendation as more evidence becomes available.
In situations where there is uncertainty regarding myocarditis diagnosis, discussion should occur with an appropriate physician or nurse practitioner on potential options for (re)immunization with the same or alternative COVID-19 vaccine, including a riskbenefit analysis for the individual. The individual qualifies for a medical exemption if the physician or nurse practitioner has determined that the individual is unable to receive any COVID-19 vaccine. Those with a history compatible with pericarditis and who either had no cardiac workup or had normal cardiac investigations, can be re(immunized) once they are symptom free and at least 90 days has passed since vaccination. Some people with confirmed myocarditis and/or pericarditis may choose to receive another dose of vaccine after discussing the risks and benefits with their healthcare provider. Individuals can be revaccinated once they are symptom free and at least 90 days has passed since vaccination. If another dose of vaccine is offered, they should be offered the Pfizer-BioNTech 30 mcg vaccine due to the lower reported rate of myocarditis and/or pericarditis following the Pfizer-BioNTech 30mcg vaccine compared to the Moderna 100 mcg vaccine. Informed consent should include discussion about the unknown risk of recurrence of myocarditis and/or pericarditis following receipt of additional doses of Pfizer-BioNTech COVID-19 vaccine in individuals with a history of confirmed myocarditis and/or pericarditis after a previous dose of mRNA COVID-19 vaccine, as well as the need to seek immediate medical assessment and care should symptoms develop.

# Severe Allergic Reaction or Anaphylaxis following a COVID-19 vaccine
In individuals with a history of a severe, immediate (4h following vaccination) allergic reaction (e.g., anaphylaxis) after previous administration of an mRNA COVID-19 vaccine, re-vaccination (i.e. administration of a subsequent dose in the series when indicated) may be offered with the same vaccine or the same mRNA platform if a risk assessment deems that the benefits outweigh the potential risks for the individual and if informed consent is provided. The risk of a severe immediate allergic reaction after re-immunization appears to be low and no long-term morbidity has been associated with re-vaccination.
- Consultation with an allergist may be sought prior to re-vaccination.
- If re-vaccinated, vaccine administration should be done in a controlled setting with expertise and equipment to manage allergic reactions. Individuals should be observed for at least 30 minutes after re-vaccination. For example, a longer period of observation is warranted for individuals exhibiting any symptom suggestive of an evolving AEFI at the end of the 30 minute observation period.
For those with a previous history of allergy to an mRNA vaccine, re-vaccination with an mRNA vaccine is preferred over a viral vector vaccine due to the better effectiveness and immunogenicity of mRNA vaccines and the possible adverse effects specifically associated with viral vector vaccines (e.g., Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT), capillary leak syndrome (CLS), and Guillain-Barre Syndrome (GBS)).
In individuals with a history of a severe, immediate (4h following vaccination) allergic reaction (e.g., anaphylaxis) after previous administration of a viral vector COVID-19 vaccine, re-vaccination may be offered with an mRNA platform if a risk assessment deems that the benefits outweigh the potential risks for the individual and if informed consent is provided. If re-vaccinated, individuals should be observed for at least 30 minutes after re-vaccination.
A medical exemption may be issued if discussion has occurred with an appropriate physician or nurse practitioner on potential options for (re)immunization with the same or alternative COVID-19 vaccine, including a risk-benefit analysis for the individual, and the physician or nurse practitioner has determined that the individual cannot receive any COVID-19 vaccine with the currently available mitigation strategies.

# Other allergies
Individuals with other types of non-severe allergies can receive COVID-19 vaccines as outlined in the MOH's Vaccination Recommendations for Special Populations. These allergies do not on their own constitute the grounds for a medical exemption. For more information on the management of individuals with allergies, please see the MOH's Vaccination Recommendations for Special Populations.

# Serious Adverse Event Following COVID-19 Immunization (AEFI)
Individuals who experience a serious adverse event following immunization (AEFI) (e.g., hospitalization, persistent or significant disability/incapacity) with a COVID-19 vaccine should be medically assessed by an appropriate physician or nurse practitioner, and the event should be reported to their local public health unit (PHU). This may include clinical syndromes such as Guillain-Barre Syndrome (GBS). The Health Protection and Promotion Act (HPPA) mandates reporting of AEFIs by healthcare providers who administer immunizations (e.g., registered nurses, nurse practitioners, pharmacists, and physicians).
AEFI reports received by PHUs are investigated, assessed, and documented according to provincial surveillance guidelines, as required by the Ontario Public Health Standards (OPHS). For serious AEFIs, this includes referral to an appropriate physician or nurse practitioner for diagnosis/management and expert assessment for recommendation for subsequent immunization (e.g., the Special Immunization Clinic (SIC) Network, immunologist, etc.). This assessment will include a detailed assessment of the adverse event including investigations and diagnosis, and assessment for alternative etiology for the event. Discussion with the patient should then consider the event and the personal and epidemiological context (in terms of risk of COVID-19 infection) for the patient, and the risks and benefits regarding recommendations/options for immunization. The individual qualifies for a medical exemption if the appropriate physician or nurse practitioner (e.g., immunologist, SIC network, Medical Officer of Health, etc.) determines that the individual is unable to receive any COVID-19 vaccine after the event has been medically evaluated AND a discussion has occurred on the individual's risks and benefits of potential options for immunization with the same or alternative COVID-19 vaccine.
There are very few serious AEFIs that would result in a medical exemption to COVID-19 vaccination.

# Other
Actively receiving monoclonal antibody or convalescent plasma therapy for the treatment or prevention of COVID-19 disease Individuals who are actively receiving monoclonal antibody or convalescent plasma therapy for the treatment or prevention of COVID-19 disease should not receive a COVID-19 vaccine (NACI). This is a time-limited (temporary) precaution. COVID-19 vaccines may be administered to these individuals once therapy is discontinued, with the timing of administration and potential for immune interference evaluated on a case-by-case basis by an appropriate physician or nurse practitioner. A medical exemption may be issued only if the individual is actively receiving therapy.

# Actively receiving or recently completed immunosuppressing therapy anticipated to significantly blunt vaccine response
Individuals who are actively receiving or recently completed an immunosuppressive therapy listed in the table below may be advised by their physician or nurse practitioner to defer COVID-19 vaccination to a later point to optimize immune response to the COVID-19 vaccine and minimize delays in management of their underlying condition. This is a time-limited (temporary) precaution. The recommended maximum deferral duration following completion of specific therapies is listed in the table below.
COVID-19 vaccines may be administered to these individuals once therapy is discontinued, with timing of administration evaluated on a case-by-case basis by an appropriate physician or nurse practitioner. Discussion with the patient should then consider their medical condition and the personal and epidemiological context (in terms of risk of COVID-19 infection) for the patient, and the risks and benefits regarding timing and recommendations/options for immunization. A time-limited medical exemption may be issued only if the appropriate physician or nurse practitioner has recommended that the individual defer COVID-19 vaccination to a later point to optimize their immune response.