Summary of The National Advisory Committee On Immunization (Naci) Statement of DECEMBER 3, 2021

SUMMARY OF THE NATIONAL
ADVISORY COMMITTEE ON
IMMUNIZATION (NACI)
STATEMENT OF
DECEMBER 3, 2021
Guidance on booster COVID-19 vaccine doses in
Canada – Update December 3, 2021
OVERVIEW
 On December 3, 2021, the Public Health Agency of Canada (PHAC) released updated
guidance from the National Advisory Committee on Immunization (NACI) on booster
doses of COVID-19 vaccine. These recommendations are based on current scientific
evidence and NACI's expert opinion.
 Cases of COVID-19 are increasing globally and in Canada. Variants, including the Delta
variant, continue to circulate and cause serious illness. A new variant of concern,
Omicron, has also been detected. Evidence on this new variant is still being collected.
 In November 2021, Health Canada authorized the use of the Pfizer-BioNTech Comirnaty
30 mcg vaccine and the Moderna Spikevax 50 mcg vaccine as booster doses in those
18 years of age and older at least 6 months after completion of a primary series.
 NACI has reviewed the latest data that suggest protection against infection decreases
over time since completion of a primary COVID-19 vaccine series. Protection against
severe illness remains generally high, but may decrease over time for some people,
such as older adults.
 Booster doses of COVID-19 mRNA vaccines can increase the immune response and
are expected to offer enhanced protection against infection and severe disease and may
help reduce spread of infection. Booster doses have a favourable safety profile that is
comparable to the primary series.
 The Council of Chief Medical Officers of Health have updated the COVID-19
Immunization Response Goals to include preserving health system capacity and
reducing transmission to protect high risk populations while minimizing serious illness
and overall deaths.
After reviewing the recent evidence and the evolving COVID-19 pandemic in the
Canadian context, NACI has updated its booster recommendations:
 NACI strongly recommends a booster dose of an authorized mRNA COVID-19

vaccine should be offered at least 6 months after completion of a primary COVID-
19 vaccine series to the following groups:
o People aged 50 years and older
o Adults living in long-term care homes for seniors or other congregate living
settings that provide care for seniors
o Recipients of a viral vector vaccine series completed with only viral vector
vaccines (AstraZeneca/COVISHIELD or Janssen COVID-19 vaccine)
o Adults in or from First Nations, Inuit and Métis communities
o All frontline healthcare workers having direct in-person contact with
patients
SUMMARY OF NATIONAL ADVISORY COMMITTEE ON IMMUNIZATION (NACI) STATEMENT OF DECEMBER 3, 2021 | 2

 NACI now also recommends that a booster dose of an authorized mRNA COVID-19
vaccine may be offered to adults 18 to 49 years of age at least 6 months after
completion of a primary COVID-19 vaccine series with consideration of
jurisdictional and individual risks as outlined in the full NACI Statement.
To see the full guidance, including a summary of the evidence and rationale behind these
recommendations, please visit NACI Guidance on booster COVID-19 vaccine doses in Canada
– Update December 3, 2021.
WHAT YOU NEED TO KNOW

 Cases of COVID-19 are increasing and variants, including the Delta variant, are
circulating in Canada and in various parts of the world. A new variant of concern,
Omicron, has also recently been detected. Evidence on this new variant is still being
collected.
 In many countries, the rate of severe COVID-19 disease and other outcomes has
increased following rising infection rates. Cases have also been rising slightly in some
areas of Canada.
 A complete COVID-19 vaccine series continues to provide excellent protection against

serious illness for most people. Over time, some people may be less protected against
serious illness, such as older adults.
 Recently, evidence suggests vaccine effectiveness against infection with SARS-CoV-2,

the virus that causes COVID-19, is decreasing over time following completion of the
primary series. A booster dose could help restore protection against infection that may
have decreased over time.
 Clinical trial data show that a booster dose of an mRNA COVID-19 vaccine produces a
robust immune response and has a favourable safety profile comparable to the second
dose of the primary series. Myocarditis and/or pericarditis after mRNA vaccination
remain rare. In Israel, the rates of myocarditis and/or pericarditis have been lower than
what was observed with the second dose of the primary series, but higher than what was
observed with the first dose.
 Real-world data suggest that a booster dose of mRNA COVID-19 vaccine provides very
good short-term effectiveness against SARS-CoV-2 infection. Long-term effectiveness of
booster doses will continue to be monitored.
 A longer interval between the primary series and a booster dose could improve or
extend the immune response to the booster dose.

 NACI continues to recommend that a complete series with an mRNA COVID-19 vaccine
should be offered to individuals in the authorized age groups without contraindications to
the vaccine. The Pfizer-BioNTech Comirnaty 30 mcg product is preferred for the primary
series in those 12 to 29 years of age and may be preferred for the booster dose in those
18 to 29 years of age due to the lower risk of myocarditis/pericarditis with this vaccine. In
people over 30 years of age, either mRNA vaccine can be used for the booster.
 Adults who are moderately to severely immunocompromised who have received a three-
dose primary series are included in those who may receive a booster dose. Data on a
fourth dose of a COVID-19 vaccine after the recommended three-dose primary series in
this population is currently limited. These individuals may receive a booster at least 6
months after receiving their last dose.
 If offering the Moderna vaccine as a booster, the 100 mcg dose may be preferred for
adults who are moderately to severely immunocompromised, as well as adults living in
long-term care for seniors or other congregate living settings that provide care for
seniors based on the discretion of healthcare providers.
 Pregnant or breastfeeding individuals were excluded from clinical trials of mRNA booster
doses, but no maternal or neonatal safety signals have been detected in pregnant or
breastfeeding individuals who have received mRNA COVID-19 vaccines. Pregnant or
breastfeeding adults are included in those who may receive a booster dose.
 In addition to high vaccine coverage, public health measures continue to be essential to

reduce and control transmission of the virus, especially variants.
 NACI will continue to review and monitor the evidence on booster doses as it emerges
and will update their recommendations as needed.
To see the full guidance, including a summary of the evidence and rationale behind these
recommendations, please visit NACI Guidance on booster COVID-19 vaccine doses in Canada
– Update December 3, 2021.

QUOTES
“NACI has continued to closely monitor the evidence on the benefit and need for booster doses
in Canada, and is now providing updated advice on the use of booster COVID-19 vaccine
doses. Although protection against severe disease remains high in the general population, we
know that protection against infection can decrease over time. We have also seen an increase
in the risk of severe disease for select groups who are vaccinated, particularly older adults.
Offering booster doses will help ensure that protection against severe disease remains high,
and may have an impact on spread in the community as well.
It is important to note that there is no information yet on the impact of the new variant, Omicron,
on the effectiveness of the vaccine. NACI will continue to monitor and provide updated and
timely advice as necessary.”
- Dr. Shelley Deeks, NACI Chair
“NACI’s review of the latest available evidence from ongoing monitoring of COVID-19 vaccines
safety and effectiveness reassures us that there remains no widespread decrease in protection
against severe disease in the general population in Canada. However, waning protection trends
observed in other countries give us cause for concern. As such, NACI’s updated evidence-
informed advice on booster doses will assist health authorities in vaccine program planning and
delivery to ensure Canadians are provided with the best possible protection as the situation
evolves.
Nevertheless, while booster doses provide an opportunity to maintain and enhance protection
against infection and severe disease, getting more people to complete their primary series
remains a key focus of the COVID-19 immunization effort in Canada. Importantly, regardless of
which virus variant is circulating, public health measures and individual precautions continue to
be an essential component of the pandemic response in Canada. Using layers of these non-
pharmaceutical protections in conjunction with strategic use of approved COVID-19 vaccines
remains our best approach to decrease the risk of infection and severe disease.”
- Dr. Theresa Tam, Chief Public Health Officer

NACI FORWARD AGENDA
NACI continues to actively review emerging evidence on COVID-19 vaccines. Upcoming
recommendations may include new advice on:
 Advice on vaccination for individuals with a history of myocarditis/pericarditis after a

previous dose of vaccine
 Recommendations on the use of the Moderna COVID-19 vaccine in children, pending a

regulatory decision by Health Canada
 Recommendations on the use of the Novavax COVID-19 vaccine, pending a regulatory

decision by Health Canada
 Recommendations on the use of the Medicago COVID-19 vaccine, pending a regulatory

decision by Health Canada

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SUMMARY OF THE NATIONAL

 NACI strongly recommends a booster dose of an authorized mRNA COVID-19

SUMMARY OF NATIONAL ADVISORY COMMITTEE ON IMMUNIZATION (NACI) STATEMENT OF DECEMBER 3, 2021 | 2

WHAT YOU NEED TO KNOW

 A complete COVID-19 vaccine series continues to provide excellent protection against

 Recently, evidence suggests vaccine effectiveness against infection with SARS-CoV-2,

SUMMARY OF NATIONAL ADVISORY COMMITTEE ON IMMUNIZATION (NACI) STATEMENT OF DECEMBER 3, 2021 | 3

 In addition to high vaccine coverage, public health measures continue to be essential to

SUMMARY OF NATIONAL ADVISORY COMMITTEE ON IMMUNIZATION (NACI) STATEMENT OF DECEMBER 3, 2021 | 4

- Dr. Shelley Deeks, NACI Chair

- Dr. Theresa Tam, Chief Public Health Officer

SUMMARY OF NATIONAL ADVISORY COMMITTEE ON IMMUNIZATION (NACI) STATEMENT OF DECEMBER 3, 2021 | 5

 Advice on vaccination for individuals with a history of myocarditis/pericarditis after a

 Recommendations on the use of the Moderna COVID-19 vaccine in children, pending a

 Recommendations on the use of the Novavax COVID-19 vaccine, pending a regulatory

 Recommendations on the use of the Medicago COVID-19 vaccine, pending a regulatory

SUMMARY OF NATIONAL ADVISORY COMMITTEE ON IMMUNIZATION (NACI) STATEMENT OF DECEMBER 3, 2021 | 6

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