# Introduction
This Canadian Thoracic Society (CTS) document aims to provide guidance and relevant information for respiratory health care professionals on COVID-19 vaccination in Canada. Due to limited data, there are areas of uncertainty which have prompted the CTS, and several other national and international Specialty Societies, to provide advice on vaccination based on available evidence and expertise. We highlight this important information in this paper. A Frequently Asked Questions (FAQ) section of this document seeks to address some of the concerns that may arise in discussion with patients who are immunocompromised, treated with biologic therapy or long-term steroids, pre-or post-transplant, etc. We plan to update this guidance as new information becomes available and recommend periodically checking the Canadian Thoracic Society website (/) for updates.
It is important to note that even after vaccination other recommended public health measures, including frequent hand washing or use of alcohol-based hand sanitizers, wearing face masks, and physical distancing should continue to be observed; this is especially important in those with chronic medical conditions.
In Canada, there is a gap in the knowledge about the rate of vaccination in patients with respiratory diseases. However, it is clear from Canadian studies  that address vaccine uptake that the vaccination rates for seasonal influenza and for pneumococcal infection are below the ideal level of 80%. 7 A recommendation or contact (visit) with a health care professional was identified in several studies 2,8,9 as an important predictor influencing an individual's decision to be vaccinated. The study by Bourbeau et al. 2 found that COPD patients in Quebec and Ontario who had regular contact with their physician had vaccination rates of 80% for seasonal influenza, as reported by their primary care doctors. In the Boerner et al. study, 8 participants mentioned a physician recommendation along with trust in their physicians as a significant factor in their vaccination decision.
Therefore, the role of physicians, respiratory health care professionals and educators as advocates for vaccination along with consistent messaging on COVID-19 vaccination will likely be effective in improving vaccination rates in this vulnerable population.

# Drugs and COVID-19 vaccines authorized or in progress by Health Canada as of February 2021
- List of authorized drugs, vaccines and expanded indications for COVID-19 - Pfizer-BioNTech COVID-19 vaccine: What you should know - Moderna COVID-19 vaccine: What you should know

# Summary of efficacy and safety of the Pfizer-BioNTech and Moderna vaccines approved by Health Canada:
The first 2 COVID-19 vaccines to receive Health Canada approval for use (Pfizer-BioNTech and Moderna) have shown over 80% efficacy for preventing symptomatic and severe disease. The duration of follow up has been limited to 2-4 months. It is not known how long the protection will last after 1 or both injections. New variants are already emerging, and it is too early to know if it will affect vaccine efficacy.
From the clinical trials, both vaccines are safe. Severe adverse events are rare and usually self-limited. However local and systemic side effects are in keeping with known side effects associated with vaccines and are usually self-limited. Long-term side effects are highly unlikely. Regarding anaphylaxis, Moderna has reported 2.5 cases per million (as of Jan 10, 2021: MMWR January 29, 2021/670 (4): 125-129) and Pfizer 11 cases per million (as of Dec 23, 2020: MMWR: January 15, 2021/ 70 (2): 46-51). The majority of cases involved patients with documented/known allergies or allergic reaction, and 1/3 to 1/2 had previous history of anaphylaxis.

# Recommendations on the use of COVID-19 vaccines in Canada
The National Advisory Committee on Immunization (NACI) provides the Public Health Agency of Canada (PHAC) with independent, ongoing and timely medical, scientific, and public health advice in response to questions from PHAC relating to immunization. NACI has provided independent expert advice regarding priority populations for early vaccinations.

# NACI recommendations for priority for early COVID-19 vaccination to the following populations:
- residents and staff of shared living settings who provide care for seniors - adults 70 years of age and older, with order of priority: 1. beginning with adults 80 years of age and older 2. decreasing the age limit by 5-year increments to age 70 years as supply becomes available - health care workers who have direct contact with patients, including:
- those who work in health care settings 2. personal support workers - adults in Indigenous communities As additional COVID-19 vaccine(s) and supplies become available, the following populations should be offered vaccinations:
- health care workers not included in the initial rollout - residents and staff of all other shared living settings, such as: o homeless shelters o correctional facilities o housing for migrant workers - essential workers who face additional risks to maintain services for the functioning of society

# Prioritization of Canadians with lung disease in the vaccination rollout
The COVID-19 Respiratory Roundtable led by the CTS issued a joint statement in January urging the federal, provincial and territorial governments to prioritize people living with lung disease who are at higher risk for more serious COVID-19 complications in the vaccination rollout. In February, NACI released recommendations on the prioritization of key populations for COVID-19 immunization which includes chronic lung disease as a risk factor for poor outcome. PDF document (People who are at risk of more severe disease or outcomes from COVID-19)

# Provincial and Territorial vaccination rollout plans
While NACI provided guidance on vaccination priorities, vaccination rollout plans are province-and territoryspecific. For the latest detailed vaccination rollout plans, visit this website and go to the vaccine page for your province or territory: #a3 NACI recommendations on the use of COVID-19 vaccines 10 (updated recommendations Jan 12, 2021)

# NACI recommendations are now worded as "should" (strong) or "may" (discretionary).
A strong recommendation applies to most populations/individuals and should be followed unless a clear and compelling rationale for an alternative approach.
A complete vaccine series with a currently authorized COVID-19 vaccine should be offered to:
- Individuals in the authorized age group without contraindications to the vaccine. In the context of limited vaccine supply, initial doses of COVID-19 vaccine(s) should be prioritized for the key populations outlined in NACI's Guidance on the prioritization of key populations for COVID-19 immunization which now lists chronic lung disease as a risk factor for poor outcomes.
A discretionary recommendation may be offered for some population/individuals in some circumstances.
A complete vaccine series with a currently authorized COVID-19 vaccine may be offered to:
- Individuals in the authorized age group without contraindications to the vaccine who have had previously polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection. In the context of limited vaccine supply, initial doses may be prioritized for those who have not had previously PCR-confirmed SARS-CoV-2 infection. Testing for previous SARS-CoV-2 infection is not needed prior to COVID-19 vaccination.
For some specific populations who were either excluded from, or were represented by small numbers of participants in clinical trials, NACI recommends that a complete vaccine series with a currently authorized COVID-19 vaccine may be offered, if a risk assessment deems that the benefits of vaccination outweigh the potential risks for the individual (e.g., where the risk of severe outcomes of COVID-19 and/or risk of exposure to SARS-CoV-2 is high) or for the fetus/infant (in the case of pregnancy/breastfeeding), and if informed consent includes discussion about the insufficient evidence in these populations:
- Immunosuppressed due to disease or treatment - Individuals with an autoimmune condition - Pregnant or breastfeeding women These recommendations may change as more evidence on safety and/or effectiveness in these populations becomes available. The complete list of NACI recommendations are available at: #a7

# Contraindications
The Health Canada approved COVID-19 vaccines are contraindicated in individuals with a history of anaphylaxis after previous administration of the vaccine. Vaccine is also contraindicated in persons with proven immediate or anaphylactic hypersensitivity to any component of the vaccine or its packaging. Clinical trials of the authorized COVID-19 vaccines excluded individuals with a history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine. Individuals with a history of severe allergic reaction to a component of the COVID-19 vaccine should not receive the 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.

# Advice for specific populations

# Children under 16 years of age
The Pfizer-BioNTech COVID-19 vaccine is currently approved for individuals who are 16 years of age and older, and the Moderna COVID-19 vaccine for 18 years of age and older. The COVID-19 vaccine(s) should not be offered to individuals who are not in the authorized age group. There are ongoing clinical trials on vaccine efficacy and safety in children aged 12 years and older and more data will be available in the coming months.

# Advice for pregnant and breastfeeding women
Please see the advice on the Society of Obstetricians and Gynaecologists of Canada (SOGC) website here: Nearly everyone will be able to safely receive the COVID-19 vaccine, although a very small number of people may need to avoid vaccination due to severe allergies to parts of the vaccine.
- If you are taking treatment for TB disease or latent TB infection, it is safe to receive the COVID-19 vaccine when it is offered to you. - If you are not tolerating your TB treatment, you should wait until your treatment is stable before receiving the COVID-19 vaccine. It is not a safety concern, but it is important to separate the side effects of your TB treatment from a potential side effect of the COVID-19 vaccine.

# Advice for immunosuppressed individuals including individuals receiving immunosuppressant therapy
NACI recommends that a complete COVID-19 vaccine series may be offered to individuals who are immunosuppressed due to disease or treatment in the authorized age group in this population, if a risk assessment deems that the benefits outweigh the potential risks. Informed consent prior to vaccination should include a discussion about the absence of evidence on the use of COVID-19 vaccine in this population.
- Currently, there are no data on COVID-19 vaccination in individuals who are immunosuppressed. Participants in the mRNA COVID-19 vaccine clinical trials only included individuals who were not immunosuppressed, and those not receiving immunosuppressive therapy during the trial.
- In general, non-replicating vaccines may be administered to immunocompromised people because the antigens in the vaccine cannot replicate. However, the magnitude and duration of vaccine-induced immunity are often reduced. It is currently unknown whether immunocompromised individuals will be able to mount an immune response to mRNA vaccines. - The relative degree of immunodeficiency in individuals who are immunocompromised varies depending on the underlying condition, the progression of disease, and use of medications that suppress immune function. Therefore, the balance of benefits and risks must be made on a case-by-case basis. - Immunocompromised persons, including individuals receiving immunosuppressant therapy, may have a diminished immune response to the vaccine. - Although inactivated vaccines can be safely administered at any time before, during or after immunosuppression, inactivated vaccines should be administered at least 14 days before initiation of immunosuppressive therapy to optimize immunogenicity. 11 - Active surveillance in these vaccine recipients is strongly encouraged.
- NACI and CTS will monitor the evidence as it evolves, and update these recommendations as needed.

# Advice for individuals treated with a biological therapy for Asthma
The two large randomized controlled trials (RCTs) of the mRNA vaccines published in the NEJM (Pfizer-BioNTech and Moderna) did not include participants on (asthma) biologics. There is no biological rationale as to why anti-IgE, anti-IL5, anti-IL5R or even anti-IL4/13 therapies should place patients at higher risk for adverse events. Of course, many of these patients ALSO have a history of severe allergy & anaphylaxis. The COVID-19 vaccine RCTs generally excluded these patients but, in post-emergency use authorization, the incidence of anaphylaxis has been about 1/100,000 vs. 1/1,000,000 for other vaccines. To our knowledge, none have resulted in fatality, and all have responded well to Epi-Pen and/or brief ER management.
Thus, patients with asthma on a biologic therapy should be advised: 1) risks are as above, but that benefits outweigh these; 2) have the vaccine when offered, but schedule for a site with onsite EMS/physician coverage; 3) those with a history of allergies to advise the vaccination staff, and to have their Epi-Pen -where relevantwith them, current, and visible on the table.
Advice for individuals with an autoimmune condition NACI recommends that a complete vaccine series with a COVID-19 vaccine may be offered to individuals with an autoimmune condition in the authorized age group in these populations if a risk assessment deems that the benefits outweigh the potential risks for the individual, and if informed consent includes discussion about the insufficiency of evidence on the use of COVID-19 vaccine in these populations.

# Responses to Frequently Asked Questions by Patients 1) Can I have a flu vaccination or the pneumococcal vaccination at the same time as a COVID vaccine?
NACI recommends that COVID-19 vaccines should not be given simultaneously with other vaccines (live or inactivated). Currently, no data exist on the simultaneous administration of COVID-19 vaccine with other vaccines. In the absence of evidence, attempts should be made to avoid simultaneous administration to maximize benefits of COVID-19 vaccination while minimizing any risks of harm, including the potential for immune interference or the erroneous attribution of an adverse event following immunization to a particular vaccine. However, if a COVID-19 vaccine is inadvertently administered at the same time as another vaccine, neither dose should be repeated.
In the absence of evidence, it would be prudent to wait for a period of at least 28 days after the administration of the complete two-dose vaccine series of an mRNA COVID-19 vaccine before the administration of another vaccine (except in the case where another vaccine is required for post-exposure prophylaxis) due to the elicitation of an inflammatory cytokine response. 10 It would be prudent to wait for a period of at least 14 days after the administration of another vaccine before administrating a COVID-19 vaccine to prevent erroneous attribution of an adverse event following immunization to a particular vaccine. 10
Refer to Simultaneous administration with other vaccines 10 and Timing of Vaccine Administration in the Canadian Immunization Guide, Part 1 -Key Immunization Information for additional information on simultaneous administration of other vaccines in general.

# 2) Which COVID vaccine should I have?
The vaccines that are currently approved by Health Canada are effective and safe. However, many more vaccines will be approved over time. We will learn more about differences on the efficacy and safety profile of each of these vaccines. Based on updated knowledge from clinical trials, it is possible that public health authorities will consider making recommendations of preferable use of certain vaccines by age groups or for population with specific medical conditions.

# 3) Should I receive the vaccine and is the vaccine going to work considering I am immunocompromised?
Non-replicating vaccines may be administered to immunocompromised people because the antigens in the vaccine cannot replicate. However, the magnitude and duration of vaccine-induced immunity are often reduced.
It is currently unknown whether immunocompromised individuals will be able to mount an immune response to mRNA vaccines.

# 4) Should I stop taking any of my medications (such as immunosuppressive medications) to make sure the vaccine works well?
Immunocompromised persons, including individuals receiving immunosuppressant therapy, may have a diminished immune response to the vaccine. The Canadian Immunization Guide recommends inactivated vaccines be administered at least 14 days before initiation of immunosuppressive therapy to optimize immunogenicity.

# 5) I have been suffering from "Long COVID" -does this mean I shouldn't have the vaccine?
A prior SARS-CoV-2 infection may not provide adequate protection for reinfection, therefore, vaccination against COVID-19 is recommended. However, in setting of limited vaccine supply, doses may be prioritized for those who have not had previously PCR-confirmed SARS-CoV-2 infection.

# 6) What is the rationale for changing the interval between first and second doses?
The NACI statement on vaccine administration and timing of vaccine administration can be found here: #b4  

# Useful Links
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