Healthcare Practitioner COVID-19 Vaccine FAQs

COVID-19 Vaccine-Specific Information

Vaccine Product Information

• Pfizer-BioNTech Comirnaty™ COVID-19 Vaccine  - product monograph (for adult and pediatric formulation)
• Pfizer-BioNTech - website
• Moderna Spikevax™ - product monograph
• Moderna -  website
• COVISHIELD - product monograph
• AstraZeneca Vaxzevria™ COVID-19 Vaccine - product monograph
• Janssen (Johnson & Johnson) COVID-19 Vaccine - product monograph

General Resources: 

• SK Drug Plan & Extended Benefits Branch - COVID-19 Immunization Program
• Saskatchewan Health Authority - Vaccine Information for HCPs
• Saskatchewan Health Authority- Vaccine Uptake Support
• eHealth COVID-19 Immunization Manual 
• Health Canada - COVID-19 page
• Health Canada - COVID-19 Vaccine page
• National Collaborating Centre for Infectious Diseases (NCCID) - home page
• Association of Medical Microbiology and Infectious Disease Canada - home page

Recommendations for Vaccine Use

• National Advisory Committee for Immunizations (NACI): Vaccine Statements (Recommendations, Rapid Responses, Summaries) under COVID-19 tab 
• Public Health Agency of Canada (PHAC): COVID-19 Vaccine Tool Kit for Health Care Providers
• Saskatchewan Health Authority: COVID-19 Vaccine Information
• The Society of Obstetricians and Gynaecologists of Canada (SOGC)- Statement on COVID-19 Vaccination in Pregnancy 
• Saskatchewan Cancer Agency - COVID-19 mRNA Vaccine in Adult Patients with Cancer
• The Canadian Network of MS Clinics - The CNMSC COVID-19 Recommendations

More Vaccine Resources

• Saskatchewan Immunization Manual (SIM) Chapter 10 Biological Products provides links to the product monographs 
• For healthcare providers:
  • CanVax
  • Centre for Effective Practice

We were not able to find any information that suggests being on clozapine would be a contraindication to receiving the COVID-19 vaccine. However, the following information may be helpful for clinicians and patients on clozapine to consider:

• There is a single case report of increased clozapine levels and toxic effects in a patient on clozapine that received Pfizer-BioNTech Comirnaty™, but a causal relationship was neither determined nor ruled out. This would not be a reason to avoid vaccination, but may suggest increased monitoring for clozapine adverse effects following vaccination and clozapine drug level when indicated.⁽¹⁾
• There are several case studies indicate that COVID-19 infection can be associated with increased clozapine levels.^(2,3)  This may be attributed to infection-related inflammation inhibiting cytochrome P450 1A2 (CYP1A2), which then slows clozapine metabolism.⁽⁴⁾  This does not speak to any concern about giving a COVID-19 vaccine, but may explain the mechanism of increased drug levels.

Based on available information, and taking in to consideration the risk versus benefit, clozapine therapy would not be a contraindication to receiving the COVID-19 vaccine. It is important to ensure that the patient is aware of potential adverse effects, and monitor appropriately. 

References

1. Thompson D, Delorme CM, White RF, Honer WG. Elevated clozapine levels and toxic effects after SARS-CoV-2 vaccination. J Psychiatry Neurosci. 2021 Mar 5;46(2):E210-E211. doi: 10.1503/jpn.210027. PMID: 33667055; PMCID: PMC8061735.
2. Cranshaw T, Harikumar T. COVID-19 infection may cause clozapine intoxication: case report and discussion. Schizophr Bull 2020;46:751.
3. Dotson S, Hartvigsen N, Wesner T, et al. . Clozapine toxicity in the setting of COVID-19. Psychosomatics 2020;61:577–8.
4. Clark SR, Warren NS, Kim G, et al. . Elevated clozapine levels associated with infection: a systematic review. Schizophr Res 2018;192:50–6.

20 May 2021

Cases of Vaccine-induced Immune Thrombotic Thrombocytopenia (VITT) have been reported following viral vector vaccines and usually occur between 4 and 28 days after receipt.

Individuals should be monitored for symptoms -  such as persistent and severe headache, vision changes, seizures and other symptoms that resemble a stroke, such as weakness or numbness of the arms or legs, shortness of breath, abdominal or chest pain, swelling and redness in a limb and pallor and coldness in a limb, - for up to 42 days following a viral vector vaccine dose. If any of these symptoms present, individuals should seek immediate medical attention.

The rate of VITT is estimated to be between 1 per 26,000 and 1 per 100,000 persons vaccinated with a first dose of AstraZeneca Vaxzevria™. As of May 12, 2021, PHAC has estimated the rate of VITT in Canada to be 1 in 83,000 doses administered, however, as investigations continue, this rate could be as high as 1 in 55,000.

The frequency of VITT following a second dose of AstraZeneca Vaxzevria™ is currently reported as approximately 1 per 600,000 individuals vaccinated with a second dose but continues to evolve, based on vaccine safety surveillance data from the United Kingdom.

Reference

Reference

• Canadian Immunization Guidelines: Contraindications and Precautions

• When the same mRNA COVID-19 vaccine product is not readily available, or is unknown, another mRNA COVID-19 vaccine can be used. However, this may have implications for international travel (see below). 

If the 1st dose was AstraZeneca Vaxzevria™, it is recommended to receive an mRNA vaccine for the 2nd dose.

If mRNA vaccine is not an option (e.g. severe allergy to ingredients of the vaccines), AstraZeneca Vaxzevria™ may be used; AstraZeneca Vaxzevria™ is only available through Public Health.

Those planning to travel must confirm with their planned destination what vaccines and/or regimens are considered valid, and may need to consider receiving 2 doses of the same mRNA product.

• See “Who can receive 3rd and 4th doses for travel” tab.

References

• NACI: Recommendations on the use of COVID-19 vaccines under the COVID-19 tab
• eHealth: AstraZeneca Vaxzevria® COVID-19 Vaccine Benefit/Risk Form for Individuals Who Do not have a Contraindication to mRNA Vaccine
• eHealth: Additional Doses of COVID-19 Vaccine Approved for Travel

26 Oct 2021

• These doses are not mandatory and are not considered booster doses.
  • Consider necessity to travel and COVID-19 vaccine requirements at destination(s) –jurisdictions may recognize the individual’s current COVID-19 vaccination history.
• See Table below for eligible combinations.
• Doses should be separated by at least 28 days from the most recent COVID-19 immunization.
• Currently, NACI has no recommendations for more additional COVID-19 vaccine doses for the sole purpose of travel.
• There are preliminary data on the safety of third COVID-19 doses, mainly in the context of giving booster doses to immunocompromised patients. It is expected that individuals may experience mild to moderate symptoms (e.g., fever, chills, aches and pains at the injection site) after additional COVID-19 vaccine doses.

^{*AstraZeneca Vaxzevria™ is available through Public Health and may be given to individuals who have contraindications to mRNA vaccines.}

References 

• Ministry of Health: Directives to Provide Additional COVID-19 Vaccine Doses
• NACI: Recommendations on the use of COVID-19 vaccines under the COVID-19 tab

26 Oct 2021

All COVID-19 vaccines are to be injected intramuscularly and the deltoid is the preferred site.

There may be instances when the deltoid sites cannot be used or are inaccessible. Examples may include individuals with:

• Poor lymphatic circulation
  • These may include individuals with local lymphedema, upper limb amputation, axillary lymph node removal (which sometimes accompanies mastectomy), lymphangioma, arteriovenous (A-V) fistula
• Poor muscle mass
• Active cutaneous conditions (e.g. psoriasis plaques, inflammation, scars on the injection site)
• Pain at the injection site

If only one deltoid is affected, use the other deltoid.

If both deltoid sites are unsuitable for IM injection, the vastus lateralis is an alternative site.

• Landmarking for vastus lateralis
  • With the individual in the seated position, visually divide the length of the muscle from the greater trochanter of the femur to the lateral border of the kneecap into thirds.
  • Visually divide the width of the outer thigh in two with a horizontal line.
  • The injection site is in the middle third, just above the horizontal line.
    • See the vastus lateralis landmarking demonstration video. 
• Needle length
  • Needle length for IM injections is based on age, muscle mass and amount of subcutaneous tissue. For both deltoid and vastus lateralis:
    • 18 years and older: 1” to 1.5” (1” most common)
    • 5 to ≤ 17 years old: 1” (1.5” for heavier children)
      • See the CPDPP needle length video. 

• This injection site is not used for active immunization because it is less immunogenic for vaccines.

References

• NACI Recommendations on the use of COVID-19 Vaccines
• Saskatchewan Immunization Manual: Chapter 8 Administration of Biological Products
• BC Centre for Disease Control: Communicable Disease Control; Chapter 2: Immunization; Appendix B –Administration of Biological Products

18 Jun 2021

Approval for the vaccines is following the usual processes to ensure safety and efficacy. The process could be expedited because:

• more resources were made available
• resources / work were shifted from other projects to focus on the vaccine
• global agencies have been working together and sharing data
• trials were undertaken in areas with high risk of COVID-19 infection so it didn't take long to accrue data

• The two mRNA vaccines have been shown to be ~95% effective beginning one week (Pfizer-BioNTech Comirnaty™) to two weeks (Moderna Spikevax™) after the 2^nd dose. Note: The stated effectiveness of both of these vaccines are for the dominant strains of the virus and do not yet account for the variants that have popped up since.
  • Individuals may not be optimally protected until 1-2 weeks after receiving the second dose.  
  • Maximum duration of immunity is not yet known; data continue to be collected.
• AstraZeneca Vaxzevria™ and COVISHIELD have demonstrated an average efficacy of ~62% effective in those 18-64 years of age. 
  • The protection offered by the first dose of the viral vector vaccine is comparable to the efficacy observed after the second dose, with protection lasting until the second dose is administered (up to 12 weeks later).
  • Maximum duration of immunity is not yet known; data continue to be collected.
• The Janssen (Johnson & Johnson) COVID-19 vaccine had a 72% efficacy in preventing COVID infections after 28 days in the company’s U.S. trials. Note: The efficacy dropped to 66% when averaging in results from other global trials, including a South African study that factored in more transmissible variants of the COVID virus.

Short-term adverse effects are similar to those experienced with other vaccines and no safety concerns have been identified. Long-term adverse effects are not known, though most adverse effects of vaccines appear fairly soon after the dose.

In clinical trials of mRNA vaccines, some adverse events, including fever, are more frequent after the second dose; this was not the case with AstraZeneca Vaxzevria™.

Reference

• NACI: Recommendations on the use of COVID-19 vaccines under the COVID-19 tab

A traditional vaccine delivers the antigen directly by using a weakened form of the virus, while the mRNA vaccine gives the "code" for the body to make the antigen. This then triggers the immune response to make antibodies, which in turn help to fight the virus if exposed at a later date.

Reference

• CDC: Understanding mRNA COVID-19 Vaccines

19 Mar 2021

Viral vector-based vaccines use a harmless virus, such as an adenovirus, as a delivery system. This “vector” virus is not the virus that causes COVID-19. Adenoviruses are among the viruses that can cause the common cold. There are many different types of adenoviruses, and many have been used as delivery systems for other vector-based vaccines for decades.

When a person is given the vaccine, the vector virus contained within the vaccine produces the SARS-CoV-2 spike protein. This protein is found on the surface of the virus that causes COVID-19. This protein will not make you sick. It does its job and goes away. Just like with a natural infection, when the immune cells in the body are exposed to parts of the virus in a vaccine, antibodies are developed and immune cells are primed to respond to prevent infection. 

Reference 

• CDC: Understanding Viral Vector COVID-19 Vaccines

19 Mar 2021

NOTE: The COVISHIELD version of this vaccine provided a temporary supply to Canadians and is no longer authorized.

Canada has authorized 2 manufacturers of the ChAdOx1-S vaccine:

• AstraZeneca (brand name AstraZeneca Vaxzevria™ COVID-19 Vaccine)
• Verity Pharmaceuticals and Serum Institute of India (SII) in collaboration with AstraZeneca (brand name COVISHIELD)

Vaxzevria™ COVID-19 Vaccine (manufactured by AstraZeneca) and COVISHIELD (manufactured by Serum Institute of India) are ChAdOx1-S recombinant vaccines developed by AstraZeneca and Oxford University. Health Canada has reviewed the manufacturing information for these vaccines and found them to be comparable.

References 

• Health Canada: AstraZeneca Vaxzevria COVID-19 vaccine
• Vaxzevria™ Product Monograph

26 Oct 2021

No. The mRNA only goes into the cytosol of the cell. DNA (genetic information) is found in the nucleus of the cell, which the mRNA never enters.  

Reference

• NACI: Recommendations on the use of COVID-19 vaccines under the COVID-19 tab

19 Mar 2021

Unfortunately, at this time, the duration of protection after receiving one or both doses is unknown. The vaccine clinical trials have only provided us with short-term data; data continue to be collected. 

Reference

• NACI: Recommendations on the use of COVID-19 vaccines under the COVID-19 tab

19 Mar 2021