Archived 7: National Advisory Committee on Immunization: Summary of updated vaccine statement of April 23, 2021

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• Overview
• Background

Overview

COVID-19 vaccination is fundamental to ending the pandemic. The National Advisory Committee on Immunization (NACI) encourages all Canadians to get vaccinated to protect themselves, their families, and their communities from illness, hospitalizations and deaths from COVID-19.

The AstraZeneca COVID-19 vaccine is authorized for use in Canada for adults 18 years of age and over. Health Canada has determined that it is a safe and effective vaccine.

NACI has updated its recommendations on the use of the AstraZeneca vaccine in light of a rare but serious condition being referred to as Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT). Using the most recent data available, NACI assessed the benefits of the AstraZeneca COVID-19 vaccine in saving lives and protecting populations against serious complications of COVID-19 and the risks of VITT.

In this guidance statement, it is important to note that NACI provides advice on the use of the AstraZeneca COVID-19 vaccine in the context of the other COVID-19 vaccines currently authorized and available for use in Canada, in order to achieve the greatest public health benefits.

As individuals make decisions about vaccination, NACI emphasizes the importance of providing clear information that supports informed decision-making and considers both the benefits and risks of vaccination choices. This supports vaccine confidence in a context of rapid scientific advancement where guidance necessarily changes as new evidence emerges. Canadians should expect to see NACI modify its guidance as new evidence becomes available.

Provinces and territories are responsible for determining their vaccination policies, and designing and delivering their immunization programs. Jurisdictions consider NACI’s guidance in their decision-making.

Based on NACI’s initial technical briefing to provinces and territories, jurisdictions have already begun to announce their intentions regarding the use of the AstraZeneca COVID-19 vaccine, reflecting the pressing epidemiological conditions within their jurisdictions.

At this time and based on current evidence, NACI recommends that the AstraZeneca COVID-19 vaccine may be offered to individuals 30 years of age and older without contraindications, if the individual does not wish to wait for an mRNA vaccine and the benefits outweigh the risk.

NACI recognizes that public health benefit-risk analyses for the use of the AstraZeneca COVID-19 vaccine may vary between jurisdictions based on factors such as local COVID-19 epidemiology; local vaccine supply and logistics; and equity and acceptability considerations. These factors will change over time.

NACI continues to preferentially recommend authorized mRNA COVID-19 vaccines due to the excellent protection they provide, the absence of safety signals of concern and the acceptability of the vaccines by people in Canada. NACI notes that Canada has procured and is expecting enough mRNA vaccines to fully vaccinate the currently eligible Canadian population before fall 2021.

Background

NACI has updated its Recommendations on the use of COVID-19 vaccines following reports of rare but serious blood clots with low levels of blood platelets after the receipt of the AstraZeneca COVID-19 vaccine. This condition is being referred to as Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT).

Cases of VITT following the use of the AstraZeneca vaccine were first seen in Europe where the AstraZeneca vaccine has been widely used. As of April 20, 2021, three cases of VITT have been confirmed in Canada following the administration of more than 700,000 doses of the AstraZeneca vaccine. The risk of developing VITT does not seem to be related to age or sex.

On March 29, 2021, NACI recommended an immediate pause in the use of the AstraZeneca COVID-19 vaccine in those under 55 years following the reports of VITT in Europe. NACI made this recommendation out of an abundance of caution while Health Canada and other global regulators investigated the association of VITT with the AstraZeneca vaccine.  Provincial and territorial Chief Medical Officers of Health unanimously supported this decision.

On April 14, 2021, Health Canada released their safety assessment. Health Canada concluded that very rare events of blood clots associated with low levels of blood platelets following immunization with the AstraZeneca COVID-19 vaccine may be linked to the vaccine. Health Canada reaffirmed that the benefits of the AstraZeneca COVID-19 vaccine outweigh the risks and adjusted the product's labelling to reflect the available scientific evidence.

NACI met on April 13, 15, 17 and 20, 2021, to review the most up to date domestic and international evidence and guidance on VITT, and used Health Canada’s safety assessment of the AstraZeneca COVID-19 vaccine that was released on April 14, 2021, to inform its deliberations. NACI assessed the risk of developing and dying from VITT compared to COVID-19 ICU admissions and deaths that could be prevented by an early dose of the AstraZeneca COVID-19 vaccine under various COVID-19 incidence rates.

NACI’s updated recommendations are also informed by Canada’s rapidly changing COVID-19 epidemiology, including the circulation of variants of concern and hotspot areas; and a comprehensive analysis of ethics, equity, feasibility and accessibility.

NACI provides population level advice to help provinces and territories plan immunization programs in their jurisdictions. NACI recognizes that public health benefit-risk analyses for the use of the AstraZeneca COVID-19 vaccine may vary between jurisdictions due to their unique circumstances, including local epidemiology and local vaccine supply.

NACI continues to preferentially recommend authorized mRNA COVID-19 vaccines due to the excellent protection they provide, the absence of any safety signals of concern and the acceptability of the vaccines by people in Canada. NACI notes that Canada has procured and is expecting enough mRNA vaccines to fully vaccinate the currently eligible Canadian population before fall 2021.

At this time and based on current evidence, NACI recommends the AstraZeneca COVID-19 vaccine may be offered to individuals 30 years of age and older without contraindications if the individual does not wish to wait for an mRNA vaccine and if the following conditions are met:

• A benefit-risk analysis determines that the benefit of earlier vaccination with the AstraZeneca COVID-19 vaccine outweighs the risk of the individual getting COVID-19 while waiting for an mRNA COVID-19 vaccine;
• The individual provides informed consent once the benefits and risks of VITT compared to COVID-19 are clearly outlined, including how long the individual will have to wait for an mRNA vaccine and what public health measures the individual is able to take to minimize their exposure to the COVID-19 virus; and
• The individual will have to wait a long time in order to receive an mRNA vaccine.

Provincial and territorial public health officials will determine how the AstraZeneca COVID-19 vaccine will be used in their respective jurisdictions. Provinces and territories should adapt NACI’s recommended age threshold based on their local epidemiology. Health officials can refer to a Risk Assessment Framework for the use of the AstraZeneca vaccine included in the appendix of NACI’s updated statement.

Many other countries have either paused the use of the AstraZeneca COVID-19 vaccine or implemented age restrictions. Actions related to the AstraZeneca COVID-19 vaccine are expected to differ as countries have different circumstances, including different levels of COVID-19 activity and different access to COVID-19 vaccines.

Healthcare professionals should be aware of VITT, including how to diagnose and treat the condition. There is additional guidance available from the Ontario COVID-19 Science Advisory Table and Thrombosis Canada.

Individuals who receive the AstraZeneca COVID-19 vaccine should monitor their health and immediately seek medical attention if they develop symptoms of VITT, including shortness of breath, chest or abdominal pain, leg swelling, severe headaches or blurred vision, and skin bruising or a skin rash. Quick diagnosis and treatment is critical to reduce the risk of negative outcomes.

NACI will continue to closely monitor the evolving data around this rare but serious safety signal following the receipt of the AstraZeneca COVID-19 vaccine. NACI will continue to update their recommendations as needed.

To see the full update, please visit Recommendations on the use of COVID-19 vaccines.