The COVID-19 non-replicating viral vector vaccines are used to prevent COVID-19. There are two viral vector vaccines available for use in Manitoba and authorized by Health Canada: AstraZeneca/Vaxzevria^TM and Janssen.

Viral vector vaccines use a harmless virus (the vector) as a delivery system. After vaccination, the genetic material 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. The bodies immune system recognizes that the protein does not belong there and begins to build an immune response by making antibodies. It takes about two weeks for the body to fully respond to the vaccine. People cannot get COVID-19 from the viral vector vaccine and it cannot offer protection against the flu or other viruses or bacteria.

At first, Health Canada issued both the AstraZeneca/VaxzevriaTM and Janssen vaccines market authorizations with conditions to support early access to the vaccines under the interim order for COVID-19 drug authorization. This authorization gave Canadians access to safe and effective vaccines more quickly than typical circumstances. On September 16, 2021 and November 23, 2021, Health Canada approved AstraZeneca/VaxzevriaTM and Janssen respectively, under the Food and Drug Regulations (i.e., these vaccines are no longer issued market authorizations with conditions for early access under the Interim Order as sufficient data is now available to approve it under normal regulatory processes).

Yes. Studies have shown a range of effectiveness depending on study design and population. Data from clinical trials and real-world use suggests that the viral vector vaccines may be comparatively less protective than Pfizer/Comirnaty^TM and Moderna/Spikevax^TM. Clinical trials have shown that beginning two weeks after a single-dose of Janssen, it was 66% effective in protecting against COVID-19, while two-doses of AstraZeneca/Vaxzevria^TM was 76% effective. (NOTE: clinical trial data suggests that Pfizer/Comirnaty^TM and Moderna/Spikevax^TM are approximately 95% effective in preventing COVID-19).

Yes. Like all vaccines authorized for use in Canada, the COVID-19 viral vector vaccines are held to high safety, effectiveness and quality standards. After approval of a vaccine, Health Canada continues to monitor the vaccine’s safety and effectiveness.

In general, the side effects observed during the clinical trials were similar to those of other vaccines. The side effects were generally mild or moderate, and went away a few days after vaccination. These are common side effects of vaccines and are not a risk to your health. They include:

• pain, redness, itchiness, swelling and/or a warm feeling at the injection site
• body chills
• feeling tired and feverish
• headache
• muscle and joint pain
• nausea and vomiting

Over-the-counter medicines, such as acetaminophen (e.g., Tylenol®) or ibuprofen (e.g., Advil®) may be considered to help manage these symptoms (like pain or fever, respectively), if they occur after vaccination.

As with all vaccines, serious side effects are possible following vaccination with the viral vector vaccines (AstraZeneca/Vaxzevria^TM and Janssen). However, these serious side effects are rare, and include:

• Risk of blood clots with low platelets (known as Vaccine-Induced Immune Thrombotic Thrombocytopenia, or VITT). VITT can be serious, resulting in death, if not diagnosed and treated early. Signs and symptoms include:
  • shortness of breath
  • chest pain
  • leg swelling
  • persistent abdominal pain
  • neurological symptoms including sudden onset of severe or persistent worsening headaches or blurred vision and skin bruising (other than at the site of where the vaccine was given)

• Risk of Guillain-Barré syndrome (GBS). GBS is a rare neurological disorder that causes the body’s immune system to damage nerve cells. Most people fully recover from GBS. Symptoms can include:
  • Pain
  • Numbness
  • Muscle weakness, progressing to paralysis in the most severe cases

• Risk of capillary leak syndrome (CLS). A small number of reports of this rare condition have been reported following vaccination. Some of the reports reviewed were in individuals who have had this condition previously. Capillary leak syndrome is very rare, but can be serious. The condition causes fluid leakage from small blood vessels (capillaries). This can result in:
  • low blood pressure
  • swelling, mainly in the arms and legs
  • sudden weight gain
  • Immune thrombocytopenia (ITP). ITP results in low platelets (a part of the blood used for clotting) that can cause easy or excess bruising or bleeding. It can be fatal. Some of the cases of ITP after vaccination have occurred in people with a past problem with low platelets. Symptoms can include:
  • Unexplained bleeding or bruising
  • Small purplish pinpoint spots under the skin
• Venous thromboembolism (VTE). VTE causes blood clots in the deep veins such as in the legs, arms or groin that can travel to the lungs causing serious illness. Some people are more prone to VTE and should discuss this with their health care provider. (NOTE: VTE has been reported following vaccination with Janssen only). Symptoms can include:
  • leg pain
  • leg swelling
  • stomach pain that lasts for a while
  • shortness of breath
  • chest pain

People should be aware of the above symptoms in the days to weeks after vaccination, and seek medical attention immediately if they develop any of the symptoms. Be sure to tell your doctors that you received AstraZeneca/VaxzevriaTM or Janssen, and when you received it.

A limited supply of AstraZeneca/Vaxzevria^TM and Janssen is available in Manitoba for individuals aged 18 years and older who would otherwise decline vaccination if only Pfizer/Comirnaty^TM and Moderna/Spikevax^TM were available OR, in rare situations where Pfizer/Comirnaty^TM and Moderna/Spikevax^TM cannot be given (i.e., they are contraindicated for medical reasons), provided they review the benefits and risks of vaccination with their doctor or pharmacist.  

Pfizer/Comirnaty^TM and Moderna/Spikevax^TM are preferentially recommended in Manitoba given the lower effectiveness and safety concerns of AstraZeneca/Vaxzevria^TM and Janssen.

• The COVID-19 viral vector vaccine should not be given to people who are allergic to an active substance, or any ingredient of the vaccine, or if you have had a severe allergic reaction after the first dose, unless otherwise recommended by an Allergist. An allergic reaction can be life-threatening. For information about any of the COVID-19 vaccine’s ingredients, please review the vaccine manufacturer’s product monograph, available at: www.manitoba.ca/vaccine or talk to your immunizer or health care provider. There is an ingredient of both AstraZeneca/VaxzevriaTM and Janssen, known as polysorbate 80, that is a potential allergen known to cause possible allergic reactions, including serious reactions. Polysorbate 80 may be found in some medication preparations (e.g., vitamin oils, tablets, and anticancer agents) and cosmetics. Individuals with polysorbate 80 allergies may also be allergic to polyethylene glycol (PEG), another potential allergen found in many products (e.g., bowel preparation products for colonoscopy, laxatives, cough syrup, cosmetics, contact lens care solutions, skin care products, and as an additive in some food or drinks). If you are allergic to polysorbate 80 or PEG, speak with your health care provider before immunization.
• Individuals who experienced major venous or arterial thrombosis with thrombocytopenia following the first dose of a viral vector vaccine should not receive a second dose of a viral vector COVID-19 vaccine.
• Individuals who have previously experienced episodes of capillary leak syndrome should not receive AstraZeneca/Vaxzevria^TM or Janssen.
• If you have a fever or any symptoms that could be due to COVID-19, you should not be vaccinated at that time. If you were infected with COVID-19, you should get immunized after your symptoms are gone and your period of isolation is over. Talk with your health care provider if you have any new or lingering symptoms of COVID-19. Your health care provider will advise you when you may be able to receive the vaccine.

 

AstraZeneca/Vaxzevria^TM is currently approved as a two-dose vaccine in Canada. The National Advisory Committee on Immunization recommends that both doses be separated by at least eight weeks between doses.  

Janssen is currently approved as a one-dose vaccine in Canada. Due to the relatively lower effectiveness of a single-dose of Janssen, Manitoba recommends that individuals who receive a single-dose of Janssen receive an additional dose of Pfizer/Comirnaty^TM or Moderna/Spikevax^TM  a least 6 months after their Janssen dose. At present, individuals with a single dose of Janssen are eligible to apply for a Manitoba immunization card through the regular process however, individuals choosing to receive a single-dose of Janssen should be aware that a second COVID-19 vaccine may be required to ensure that their Manitoba immunization card remains valid.