COVID Vaccine-Specific Information

Vaccine Product Information
General Resources: 
Recommendations for Vaccine Use
More Vaccine FAQs
  • Saskatchewan Heath Authority Algorithms are available here to help decision making regarding use of COVID-19 vaccines in the following special populations:
    • Autoimmune conditions
    • Immunocompromised
    • Immunosuppressed / Oncology
    • Pregnancy
    • Breastfeeding
    • Previous infection - including treatment with passive antibody therapy

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 vaccine) to two weeks (Moderna vaccine) after the 2nd 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.
  • The AstraZeneca COVID-19 vaccine 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 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 the AstraZeneca COVID-19 vaccine.

  • Cases of thrombosis and thrombocytopenia, some presenting as mesenteric vein or cerebral vein/cerebral venous sinus thrombosis, have been reported in persons who had recently received COVID-19 Vaccine AstraZeneca, mostly occurring within 14 days after vaccination. The majority of reports involved women under 55, although some of this may reflect greater exposure of such individuals due to targeting of particular populations for vaccine campaigns.
  • The number of reported events exceeds those expected, and causality although not confirmed, cannot therefore be excluded. However, given the rarity of the events, and the difficulty of establishing baseline incidence since COVID-19 itself is resulting in hospitalisations with thromboembolic complications, the strength of any association is uncertain.
  • Healthcare professionals are urged to be alert for possible cases of thromboembolism, DIC or CVST occurring in vaccinated individuals.
  • Recipients should be warned to seek immediate medical attention for symptoms of thromboembolism, and especially signs of thrombocytopenia and cerebral blood clots such as easy bruising or bleeding, and persistent or severe headache, particularly beyond 3 days after vaccination.


Current Canadian Covid 19 vaccination guidelines do not include delaying Covid vaccination in patients that have recently completed antiviral therapy.

Antivirals prevent further replication of viruses. mRNA vaccines and non-replicating viral vector vaccines do not contain live replicating virus so we would not expect a diminished response to the vaccine with prior or recent receipt of anti-viral medication.

For reference, there is no reason to withhold inactivated influenza and varicella vaccines for patients taking antivirals or antibacterials.
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.

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. 

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

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

AstraZeneca 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.

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.  
No, at this time, the same product must be used for both doses. 

Saskatchewan is applying a phased approach.

Initial pilot project (mid-December 2020): Regina General Hospital

  • Healthcare workers in emergency departments, ICUs, COVID-19 wards, and COVID-19 testing & assessment staff at Regina General and Pasqua Hospitals

Phase 1 (expected end of December 2020): Priority populations at higher risk:

  • Healthcare workers
  • Staff and residents of long term care or personal care homes
  • Residents age 80 years old and older
  • Residents over the age of 50 living in remote northern communities

Phase 2 (expected April 2021): Widespread distribution of the vaccine

  • General population

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. In general, a patient receives the greatest-proportion of short-term protection after the first dose, and the purpose of additional doses is to extend protection over the longer term. However, the mRNA technology for the use in vaccines is new and data continues to be collected.