Guidance on the use of COVID-19 vaccines during the fall of 2024

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Organization: Public Health Agency of Canada

Date published: 2024-05-03
Cat.: HP5-159/1-2024E-PDF
ISSN: 978-0-660-71363-2
Pub.: 240046

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The National Advisory Committee on Immunization (NACI) is an External Advisory Body that provides the Public Health Agency of Canada (PHAC) with independent, ongoing and timely medical, scientific, and public health advice in response to questions from PHAC relating to immunization.

In addition to burden of disease and vaccine characteristics, PHAC has expanded the mandate of NACI to include the systematic consideration of programmatic factors in developing evidence based recommendations to facilitate timely decision-making for publicly funded vaccine programs at provincial and territorial levels.

The additional factors to be systematically considered by NACI include: economics, ethics, equity, feasibility, and acceptability. Not all NACI statements will require in-depth analyses of all programmatic factors. While systematic consideration of programmatic factors will be conducted using evidence-informed tools to identify distinct issues that could impact decision-making for recommendation development, only distinct issues identified as being specific to the vaccine or vaccine-preventable disease will be included.

This statement contains NACI's independent advice and recommendations, which are based upon the best current available scientific knowledge. This document is being disseminated for information purposes. People administering the vaccine should also be aware of the contents of the relevant product monograph. Recommendations for use and other information set out herein may differ from that set out in the product monographs of the Canadian manufacturers of the vaccines. Manufacturer(s) have sought approval of the vaccines and provided evidence as to its safety and efficacy only when it is used in accordance with the product monographs. NACI members and liaison members conduct themselves within the context of PHAC's Policy on Conflict of Interest, including yearly declaration of potential conflict of interest.


Over the past several years, NACI has recommended individuals receive a recently updated COVID-19 vaccine starting in the fall, when increased activity of respiratory viruses is observed. Receiving an updated vaccine is expected to offer additional protection against SARS-CoV-2 infection and severe COVID-19 disease since the strain(s) in the updated vaccines are likely to be more closely related to circulating strains, and the additional dose is expected to increase the immune response that has waned over time.

As COVID-19 activity is expected during the upcoming fall and winter months, and COVID-19 disease can compound the impact on the health system of other fall and winter respiratory viruses, NACI continues to provide early guidance on the use of COVID-19 vaccines to facilitate planning by provinces and territories. An updated vaccine to replace the current XBB.1.5 vaccine may be available starting in the fall of 2024, depending on the epidemiology of SARS-CoV-2 and recommendations of international advisory groups expected in mid-spring 2024.


On December 5, 2023, and January 19, 2024, the NACI COVID-19 Working Group (COVID-19 WG) reviewed the available information on SARS-CoV-2 epidemiology and seroprevalence, vaccine effectiveness (VE) of XBB.1.5 vaccines, and concurrent administration with COVID-19 vaccines. Preliminary cost-effectiveness estimates for a fall 2024 campaign were also reviewed.

On February 7, NACI reviewed the evidence presented to the COVID-19 WG, including evidence for children, with additional evidence on the epidemiology in adults assessed prior to reaching consensus on the proposed recommendations. The statement was approved on April 9, 2024.

Further information on NACI's process and procedures is available elsewhereFootnote 1Footnote 2.

Overview of evidence

Information available as of February 7, 2024 (except where otherwise noted) is summarized below.


Vaccine protection and hybrid immunity

Vaccine safety

For more information, please see the section on safety and adverse events in the COVID-19 vaccines chapter of the Canadian Immunization Guide (CIG).

Concurrent administration with other vaccines


Ethics, equity, feasibility, and acceptability

Timing of vaccination

For further information on NACI's recommendations on the use of COVID-19 vaccines, please refer to NACI: Statements and publications and the COVID-19 vaccines chapter of the CIG.


Please see Table 3 for an explanation of strong versus discretionary NACI recommendations.

Beginning in the fall of 2024, NACI recommends the following for the use of the most recently updated COVID-19 vaccines (only vaccines containing the latest selected strain should be used in fall 2024):

  1. COVID-19 vaccination is recommended for previously vaccinated and unvaccinated individuals at increased risk of SARS-CoV-2 infection or severe COVID-19 disease as follows:

(Strong NACI recommendation)

  1. All other previously vaccinated and unvaccinated individuals (6 months of age and older) who are not at increased risk for SARS-CoV-2 infection or severe COVID-19 disease (i.e., not on the list above) may receive the most recently updated vaccine in the fall of 2024.

(Discretionary NACI recommendation)

  1. For unvaccinated individuals 5 years of age and older who are moderately to severely immunocompromised, NACI recommends that 2 doses should be given (Strong NACI recommendation) and an additional dose (for a total of 3 doses) may be given, regardless of vaccine platform.

It should be noted that there is no change to the recommendations published in October 2023 for unvaccinated individuals 6 months to under 5 years of age who are moderately to severely immunocompromised. For these individuals, NACI reiterates the recommendation to receive one additional dose beyond the authorized 2-dose or 3-dose schedule for unvaccinated individuals 6 months to under 5 years of age (i.e., for moderately to severely immunocompromised children 6 months to under 5 years of age, 3 doses of Moderna Spikevax [preferred due to fewer doses required] or 4 doses of Pfizer-BioNTech Comirnaty), with a 4- to 8-week interval between doses. The additional doses are needed in this very young population as they are less likely to have been infected, and therefore less likely to have developed hybrid immunity, compared to individuals 5 years of age and older.

(Discretionary NACI recommendation)

For additional information on COVID-19 vaccination for these individuals, please see the COVID-19 vaccines chapter and immunization of immunocompromised persons chapter in the CIG.

Additional considerations:

Choice of COVID-19 vaccine:

Table 1. Available COVID-19 vaccines authorized and recommended by age group (based on authorized ages for currently available XBB.1.5 vaccinesFootnote a)
Recipient by age group Vaccine types authorized and available for use Recommendations on choice of latest updated COVID-19 vaccineFootnote a
6 months to under 12 years of age
  • mRNA

For children 6 months to under 5 years of age who are moderately to severely immunocompromised: Moderna Spikevax is preferredFootnote b

For all other children 6 months to under 12 years of age: Moderna Spikevax or Pfizer-BioNTech Comirnaty

12 years of age and older
  • mRNA
  • Protein subunit
Moderna Spikevax, Pfizer-BioNTech Comirnaty or Novavax Nuvaxovid


Only vaccines containing the latest selected strain should be used in fall 2024. Product choices may be more limited if not all vaccines are available with the latest strain. The specific indicated ages for updated vaccines in fall 2024 may remain the same as the currently authorized products; however, information is not yet available.

Return to footnote a referrer


Moderna Spikevax is preferred due to fewer doses required compared to Pfizer-BioNTech Comirnaty.

Return to footnote b referrer

Table 2. Comparison on the mRNA and protein sub-unit vaccines (based on previous vaccines and currently available XBB.1.5 vaccinesFootnote a)
Factor mRNA COVID-19 vaccines Protein sub-unit COVID-19 vaccine
Authorized age groupFootnote b 6 months of age and older 12 years of age and older
ImmunogenicityFootnote c XBB.1.5 products induce a good immune booster response in humans against XBB-related strains, with a lower but still boosted response against JN.1Footnote 11Footnote 12Footnote 13Footnote 14Footnote 16. The XBB.1.5 vaccine induces a good immune booster response in humans against XBB-related strains, with a lower but still boosted response against JN.1Footnote 15.
Efficacy/effectivenessFootnote c Vaccine effectiveness studies with XBB.1.5 and bivalent mRNA vaccines show increased protection against SARS-CoV-2 infection and severe COVID-19 disease compared to waned protection from previous vaccination and/or infectionFootnote 73. Good vaccine efficacy for the original product. No efficacy or effectiveness data yet available for the XBB.1.5 product.
SafetyFootnote c

mRNA COVID-19 vaccines have been shown to have a good safety profile, with over 100 million doses administered to date in Canada aloneFootnote 74.

mRNA COVID-19 vaccines have been associated with rare cases of myocarditis and/or pericarditis, particularly in adolescents and young adult males, especially after the second dose in the primary series using the original vaccine and less so after a booster using the original vaccine or bivalent vaccine. No data are currently available regarding the XBB.1.5 products.

Novavax Nuvaxovid original has been shown to have a good safety profile, with over 3 million doses administered to date, globallyFootnote 75Footnote 76Footnote 77.

Novavax Nuvaxovid original has been associated with rare cases of myocarditis and/or pericarditis based on the original vaccine. No data are currently available regarding the XBB.1.5 product.

Use in specific populations (e.g., immunocompromised, pregnant people) More data available regarding use in these populations than with protein subunit vaccines. Less data available regarding use in these populations than with mRNA vaccines.
Storage requirements and shelf-life Depending on the product, stored ultra-frozen or frozen, with refrigerator storage of thawed product from 4 to 10 weeksFootnote 78Footnote 79Footnote 80 Refrigerator storage


Some of the information in this table relates to available XBB.1.5 vaccines. The information may be relevant to the fall 2024 vaccines, however the strain(s) and other specific information regarding the fall 2024 vaccines are not yet known.

Return to footnote a referrer


The specific indicated ages for updated vaccines in fall 2024 may remain the same as current recommendations, although specific information is not yet available.

Return to footnote b referrer


Prospective head-to-head comparisons between Novavax Nuvaxovid and mRNA COVID-19 vaccines are limited. Interpreting differences in clinical data should be performed with caution.

Return to footnote c referrer

Research priorities

Continuous monitoring of vaccine acceptance and coverage in Canada, for COVID-19 vaccines and other routine vaccines, including consideration of measures that may reduce the risk of disparities in vaccine confidence and uptake across different sub-populations (including individuals in racialized and other communities experiencing inequities who may be disproportionately affected due to intersecting equity factors).

Table 3. Strength of NACI recommendations

Strength of NACI recommendation

(based on factors not isolated to strength of evidence [e.g., public health need])

Strong Discretionary
Wording "should/should not be offered" "may/may not be offered"
Rationale Known/anticipated advantages outweigh known/anticipated disadvantages ("should"), OR Known/Anticipated disadvantages outweigh known/anticipated advantages ("should not") Known/anticipated advantages are closely balanced with known/anticipated disadvantages, OR uncertainty in the evidence of advantages and disadvantages exists
Implication A strong recommendation applies to most populations/individuals and should be followed unless a clear and compelling rationale for an alternative approach is present. A discretionary recommendation may be considered for some populations/individuals in some circumstances. Alternative approaches may be reasonable.


This statement was prepared by: E Wong, R Krishnan, B Warshawsky, A Tuite, H Birdi, R Neves Miranda, K Young, MC Tunis, R Harrison, S Wilson, and S Deeks, on behalf of NACI.

NACI gratefully acknowledges the contribution of: J Daniel, M Salvadori, N Hunt, M Li, L Zhao, A Thom, and the NACI Secretariat.

NACI members: R Harrison (Chair), V Dubey (Vice-Chair), M Andrew, J Bettinger, N Brousseau, CA Buchan, H Decaluwe, P De Wals, E Dubé, K Hildebrand, K Klein, M O'Driscoll, J Papenburg, A Pham-Huy, B Sander, and S Wilson.

Liaison representatives: L Bill / M Nowgesic (Canadian Indigenous Nurses Association), LM Bucci (Canadian Public Health Association), S Buchan (Canadian Association for Immunization Research and Evaluation), E Castillo (Society of Obstetricians and Gynaecologists of Canada), J Comeau (Association of Medical Microbiology and Infectious Disease Canada), M Lavoie (Council of Chief Medical Officers of Health), J MacNeil (Centers for Disease Control and Prevention, United States), D Moore (Canadian Paediatric Society), M Naus (Canadian Immunization Committee), M Osmack (Indigenous Physicians Association of Canada), J Potter (College of Family Physicians of Canada), and A Ung (Canadian Pharmacists Association).

Ex-officio representatives: V Beswick-Escanlar (National Defence and the Canadian Armed Forces), E Henry (Centre for Immunization Programs, PHAC), M Lacroix (Public Health Ethics Consultative Group, PHAC), P Fandja (Marketed Health Products Directorate, Health Canada), M Su (COVID-19 Epidemiology and Surveillance, PHAC), S Ogunnaike-Cooke (Centre for Immunization Surveillance, PHAC), C Pham (Biologic and Radiopharmaceutical Drugs Directorate, Health Canada), M Routledge (National Microbiology Laboratory, PHAC), and T Wong (First Nations and Inuit Health Branch, Indigenous Services Canada).

NACI COVID-19 Vaccine Working Group

Members: S Wilson (Chair), M Adurogbangba, M Andrew, Y-G Bui, H Decaluwe, P De Wals, S Hosseini-Moghaddam, M Miller, D Moore, L Panagiotakopoulos, M Wallace, and M Willcott.

PHAC Participants: E Abrams, H Birdi, P Doyon-Plourde, N Islam, C Jensen, R Krishnan, SH Lim, R Neves Miranda, R Pless, M Salvadori, A Tuite, MC Tunis, B Warshawsky, E Wong, R Ximenes, K Young, and J Zafack.


Footnote 1

Ismail SJ, Langley JM, Harris TM, Warshawsky BF, Desai S, FarhangMehr M. Canada's National Advisory Committee on Immunization (NACI): Evidence-based decision-making on vaccines and immunization. Vaccine. 2010 Apr 19;28:58.

Return to footnote 1 referrer

Footnote 2

Ismail SJ, Hardy K, Tunis MC, Young K, Sicard N, Quach C. A framework for the systematic consideration of ethics, equity, feasibility, and acceptability in vaccine program recommendations. Vaccine. 2020 Aug 10;38(36):5861-76.

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Footnote 3

Public Health Agency of Canada (PHAC). COVID-19 daily epidemiology update: Testing and variants. Data cut-off March 10, 2024 [Internet]. Ottawa, ON: Government of Canada; c2024. Variants in Canada; 2024 Mar 10 [cited 2024 Apr 02]. Available from:

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Footnote 4

COVID-19 Immunity Task Force (CITF). Seroprevalence in Canada. Data cut-off November 30, 2023 [Internet]. Montreal (QC): COVID-19 Immunity Task Force (CITF): COVID-19 Immunity Task Force; 2023 Nov 30 [cited 2024 Apr 11]. Available from:

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Footnote 5

Public Health Agency of Canada (PHAC). Guidance on the use of COVID-19 vaccines in the fall: NACI, July 11, 2023 [Internet]. Ottawa (ON): Government of Canada; c2023. Duration of vaccine protection of Omicron-containing bivalent mRNA vaccines; 2023 Jul 13 [cited 2024 Apr 12]. Available from:

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Footnote 6

Public Health Agency of Canada (PHAC). Archived 50: Guidance on an additional COVID-19 booster dose in the spring of 2023 for individuals at high risk of severe illness due to COVID-19 [2023-03-03] [Internet]. Ottawa (ON): Government of Canada; c2023. Vaccine effectiveness and duration of vaccine protection of mRNA COVID-19 vaccine booster doses; 2023 Mar 03 [cited 2024 Apr 12]. Available from:

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Footnote 7

Link-Gelles R, Ciesla AA, Mak J, Miller JD, Silk BJ, Lambrou AS, et al. Early estimates of updated 2023-2024 (Monovalent XBB.1.5) COVID-19 vaccine effectiveness against symptomatic SARS-CoV-2 infection attributable to co-circulating Omicron variants among immunocompetent adults - increasing community access to testing program, United States, September 2023-January 2024. MMWR Morb Mortal Wkly Rep. 2024 Feb 01;73(4):77-83.

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Footnote 8

Hansen CH, Moustsen-Helms IR, Rasmussen M, Søborg B, Ullum H, Valentiner-Branth P. Short-term effectiveness of the XBB.1.5 updated COVID-19 vaccine against hospitalisation in Denmark: a national cohort study. Lancet Infect Dis. 2024 Feb;24(2):e73-4.

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Footnote 9

van Werkhoven CH, Valk A, Smagge B, de Melker HE, Knol MJ, Hahné SJ, et al. Early COVID-19 vaccine effectiveness of XBB.1.5 vaccine against hospitalisation and admission to intensive care, the Netherlands, 9 October to 5 December 2023. Euro Surveill. 2024 Jan;29(1).

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Footnote 10

Tartof SY, Slezak JM, Frankland TB, Puzniak L, Hong V, Ackerson BK, et al. BNT162b2 XBB1.5-adapted vaccine and COVID-19 hospital admissions and ambulatory visits in US adults. medRxiv. 2023 Dec 28:2023.12.24.23300512.

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Footnote 11

Chalkias S, McGhee N, Whatley JL, Essink B, Brosz A, Tomassini JE, et al. Interim report of the reactogenicity and immunogenicity of SARS-CoV-2 XBB-containing vaccines. J Infect Dis. 2024 Feb 13:jiae067.

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Footnote 12

Wang Q, Guo Y, Bowen A, Mellis IA, Valdez R, Gherasim C, et al. XBB.1.5 monovalent mRNA vaccine booster elicits robust neutralizing antibodies against XBB subvariants and JN.1. Cell Host Microbe. 2024 Mar 13;32(3):315,321.e3.

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Footnote 13

Gayed J, Diya O, Lowry FS, Xu X, Bangad V, Mensa F, et al. Safety and immunogenicity of the monovalent Omicron XBB.1.5-adapted BNT162b2 COVID-19 vaccine in individuals ≥12 Years old: a phase 2/3 trial. Vaccines (Basel). 2024 Jan 24;12(2):118.

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Footnote 14

Jain S, Kumar S, Lai L, Linderman S, Malik AA, Ellis ML, et al. XBB.1.5 monovalent booster improves antibody binding and neutralization against emerging SARS-CoV-2 Omicron variants. bioRxiv. 2024 Feb 05:2024.02.03.578771.

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Footnote 15

Novavax. Personal communication. 2024 Mar 06.

Return to footnote 15 referrer

Footnote 16

Moderna. Personal communication. 2023 Dec 18.

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Footnote 17

Altarawneh HN, Chemaitelly H, Ayoub HH, Tang P, Hasan MR, Yassine HM, et al. Effects of previous infection and vaccination on symptomatic Omicron infections. N Engl J Med. 2022 Jul 07;387(1):21-34.

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Footnote 18

Bobrovitz N, Ware H, Ma X, Li Z, Hosseini R, Cao C, et al. Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the omicron variant and severe disease: a systematic review and meta-regression. Lancet Infect Dis. 2023 May;23(5).

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Footnote 19

Carazo S, Skowronski DM, Brisson M, Barkati S, Sauvageau C, Brousseau N, et al. Protection against omicron (B.1.1.529) BA.2 reinfection conferred by primary omicron BA.1 or pre-omicron SARS-CoV-2 infection among health-care workers with and without mRNA vaccination: a test-negative case-control study. Lancet Infect Dis. 2023 Jan;23(1):45-55.

Return to footnote 19 referrer

Footnote 20

Carazo S, Skowronski DM, Brisson M, Sauvageau C, Brousseau N, Fafard J, et al. Prior infection- and/or vaccine-induced protection against Omicron BA.1, BA.2 and BA.4/BA.5-related hospitalisations in older adults: a test-negative case-control study in Quebec, Canada. medRxiv. 2022 Dec 27.

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Footnote 21

Cerqueira-Silva T, de Araujo Oliveira V, Paixão ES, Florentino PTV, Penna GO, Pearce N, et al. Vaccination plus previous infection: protection during the omicron wave in Brazil. Lancet Infect Dis. 2022 May 16.

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Footnote 22

Chin ET, Leidner D, Lamson L, Lucas K, Studdert DM, Goldhaber-Fiebert JD, et al. Protection against Omicron from vaccination and previous infection in a prison system. N Engl J Med. 2022 Nov 10;387(19):1770-82.

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Footnote 23

Spreco A, Dahlström Ö, Jöud A, Nordvall D, Fagerström C, Blomqvist E, et al. Effectiveness of the BNT162b2 mRNA vaccine compared with hybrid immunity in populations prioritized and non-prioritized for COVID-19 vaccination in 2021-2022: a naturalistic case-control study in Sweden. Vaccines (Basel). 2022 Aug 7;10(8):1273.

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Footnote 24

Vicentini M, Venturelli F, Mancuso P, Bisaccia E, Zerbini A, Massari M, et al. Risk of SARS-CoV-2 reinfection by vaccination status, predominant variant, and time from previous infection: a cohort study in Italy. Ssrn. 2022 Jun 09.

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Footnote 25

Lind ML, Robertson AJ, Silva J, Warner F, Coppi AC, Price N, et al. Effectiveness of primary and booster COVID-19 mRNA vaccination against Omicron variant SARS-CoV-2 infection in people with a prior SARS-CoV-2 infection. medRxiv. 2022 Apr 25.

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Footnote 26

Piechotta V, Siemens W, Thielemann I, Toews M, Koch J, Vygen-Bonnet S, et al. Safety and effectiveness of vaccines against COVID-19 in children aged 5-11 years: a systematic review and meta-analysis. Lancet Child Adolesc Health. 2023 Jun;7(6):379-91.

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Footnote 27

Watanabe A, Kani R, Iwagami M, Takagi H, Yasuhara J, Kuno T. Assessment of efficacy and safety of mRNA COVID-19 vaccines in children aged 5 to 11 years: a systematic review and meta-analysis. JAMA Pediatr. 2023 Apr 01;177(4):384-94.

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Footnote 28

Liu T, Huang P, Wu J, Chung K, Lai C, Tang H. Effectiveness of COVID-19 vaccination against multisystem inflammatory syndrome in children: a systematic review and meta-analysis. J Microbiol Immunol Infect. 2023 Dec;56(6):1299-300.

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Footnote 29

Lundberg-Morris L, Leach S, Xu Y, Martikainen J, Santosa A, Gisslén M, et al. Covid-19 vaccine effectiveness against post-covid-19 condition among 589 722 individuals in Sweden: population based cohort study. Bmj. 2023 Nov 22;383:e076990.

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Footnote 30

Marra AR, Kobayashi T, Callado GY, Pardo I, Gutfreund MC, Hsieh MK, et al. The effectiveness of COVID-19 vaccine in the prevention of post-COVID conditions: a systematic literature review and meta-analysis of the latest research. Antimicrob Steward Healthc Epidemiol. 2023 Oct 13;3(1):e168.

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Footnote 31

Jennings S, Corrin T, Waddell L. A systematic review of the evidence on the associations and safety of COVID-19 vaccination and post COVID-19 condition. Epidemiol Infect. 2023 Aug 18;151:e145.

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Footnote 32

Priddy F. Safety and immunogenicity of Moderna COVID-19 vaccine (2023-2024 formula) monovalent XBB.1.5 variant vaccine [slides presented at Advisory Committee on Immunization Practices meeting on September 12, 2023] [Internet]. U.S.: Centers for Disease Control and Prevention; 2023 Sep 12 [cited 2024 Apr 10]. Available from:

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Footnote 33

Lee IT, Cosgrove CA, Moore P, Bethune C, Nally R, Bula M, et al. A randomized trial comparing Omicron-containing boosters with the original Covid-19 vaccine mRNA-1273. medRxiv. 2023 Jan 24.

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Footnote 34

Izikson R, Brune D, Bolduc JS, Bourron P, Fournier M, Moore TM, et al. Safety and immunogenicity of a high-dose quadrivalent influenza vaccine administered concomitantly with a third dose of the mRNA-1273 SARS-CoV-2 vaccine in adults aged ≥65 years: a phase 2, randomised, open-label study. Lancet Respir Med. 2022 Apr 01;10(4):392-402.

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Footnote 35

Lazarus R, Baos S, Cappel-Porter H, Carson-Stevens A, Clout M, Culliford L, et al. Safety and immunogenicity of concomitant administration of COVID-19 vaccines (ChAdOx1 or BNT162b2) with seasonal influenza vaccines in adults in the UK (ComFluCOV): a multicentre, randomised, controlled, phase 4 trial. Lancet. 2021 Dec 18;398(10318):2277-87.

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Footnote 36

Toback S, Galiza E, Cosgrove C, Galloway J, Goodman AL, Swift PA, et al. Safety, immunogenicity, and efficacy of a COVID-19 vaccine (NVX-CoV2373) co-administered with seasonal influenza vaccines: an exploratory substudy of a randomised, observer-blinded, placebo-controlled, phase 3 trial. Lancet Respir Med. 2022 Feb;10(2):167-4.

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Footnote 37

Baj A, Gasperina DD, Focosi D, Forlani G, Ferrante FD, Novazzi F, et al. Safety and immunogenicity of synchronous COVID19 and influenza vaccination. J Clin Virol Plus. 2022 Aug;2(3):100082.

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Footnote 38

Chen W-, Lin Y-, Cheng C-, Shen C-, Ching A, Chang T-, et al. Antibodies against SARS-CoV-2 Alpha, Beta, and Gamma variants in pregnant women and their neonates under antenatal vaccination with Moderna (mRNA-1273) vaccine. Vaccines. 2022 Aug 28;10(9):1415.

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Footnote 39

Hause AM, Zhang B, Yue X, Marquez P, Myers TR, Parker C, et al. Reactogenicity of simultaneous COVID-19 mRNA booster and influenza vaccination in the US. JAMA Netw Open. 2022 Jul 01;5(7):e2222241.

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Footnote 40

Janssen C, Mosnier A, Gavazzi G, Combadière B, Crépey P, Gaillat J, et al. Coadministration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies. Hum Vaccin Immunother. 2022 Nov 30;18(6):2131166.

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Footnote 41

Shenyu W, Xiaoqian D, Bo C, Xuan D, Zeng W, Hangjie Z, et al. Immunogenicity and safety of a SARS-CoV-2 inactivated vaccine (CoronaVac) co-administered with an inactivated quadrivalent influenza vaccine: A randomized, open-label, controlled study in healthy adults aged 18 to 59 years in China. Vaccine. 2022 Aug 26;40(36):5356-65.

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Footnote 42

Stefanizzi P, Tafuri S, Bianchi FP. Immunogenicity of third dose of anti-SARS-CoV-2 vaccine co-administered with influenza vaccine: an open question. Hum Vaccin Immunother. 2022 Jul 12:2094653.

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Footnote 43

Radner H, Sieghart D, Jorda A, Fedrizzi C, Hasenöhrl T, Zdravkovic A, et al. Reduced immunogenicity of BNT162b2 booster vaccination in combination with a tetravalent influenza vaccination: results of a prospective cohort study in 838 health workers. Clin Microbiol Infect. 2023 May;29(5):635-41.

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Footnote 44

Wagenhäuser I, Reusch J, Gabel A, Höhn A, Lâm T, Almanzar G, et al. Immunogenicity and safety of coadministration of COVID-19 and influenza vaccination. European Respiratory Journal. 2023 Jan 06;61(1):2201390.

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Footnote 45

Andrews N, Stowe J, Miller E, Ramsay M. BA.1 bivalent COVID-19 vaccine use and stroke in England. Jama. 2023 Jun 15;330(2):184-5.

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Footnote 46

Dulfer EA, Geckin B, Taks EJM, GeurtsvanKessel CH, Dijkstra H, van Emst L, et al. Timing and sequence of vaccination against COVID-19 and influenza (TACTIC): a single-blind, placebo-controlled randomized clinical trial. Lancet Reg Health Eur. 2023 Apr 12;29:100628.

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Footnote 47

Fitz-Patrick D, Young M, Yacisin K, McElwee K, Belanger T, Belanger K, et al. Randomized trial to evaluate the safety, tolerability, and immunogenicity of a booster (third dose) of BNT162b2 COVID-19 vaccine coadministered with 20-valent pneumococcal conjugate vaccine in adults ≥65 years old. Vaccine. 2023 Jun 23;41(28):4190-8.

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Footnote 48

Gonen T, Barda N, Asraf K, Joseph G, Weiss-Ottolenghi Y, Doolman R, et al. Immunogenicity and reactogenicity of coadministration of COVID-19 and Influenza vaccines. JAMA Netw Open. 2023 Sep 05;6(9):e2332813.

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Footnote 49

Kenigsberg TA, Hanson KE, Klein NP, Zerbo O, Goddard K, Xu S, et al. Safety of simultaneous vaccination with COVID-19 vaccines in the Vaccine Safety Datalink. Vaccine. 2023 Jul 10;41(32):4658-65.

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Footnote 50

Lu Y, Matuska K, Nadimpalli G, Ma Y, Duma N, Zhang HT, et al. Stroke risk after COVID-19 bivalent vaccination among US older adults. Jama. 2024 Mar 19;331(11):938-50.

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Footnote 51

McElvaney OJ, Cleary B, Fraughen DD, Kelly G, McElvaney OF, Murphy MP, et al. Safety and reactogenicity of COVID-19 vaccination in severe Alpha-1 antitrypsin deficiency. Chronic Obstr Pulm Dis. 2024 Jan 25;11(1):3-12.

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Footnote 52

Moro PL, Zhang B, Ennulat C, Harris M, McVey R, Woody G, et al. Safety of co-administration of mRNA COVID-19 and seasonal inactivated influenza vaccines in the vaccine adverse event reporting system (VAERS) during July 1, 2021–June 30, 2022. Vaccine. 2023 Feb 28;41(11):1859-63.

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Footnote 53

Moscara L, Venerito V, Martinelli A, Di Lorenzo A, Toro F, Violante F, et al. Safety profile and SARS-CoV-2 breakthrough infections among HCWs receiving anti-SARS-CoV-2 and influenza vaccines simultaneously: an Italian observational study. Vaccine. 2023 Aug 31;41(38):5655-61.

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Footnote 54

Murdoch L, Quan K, Baber JA, Ho AWY, Zhang Y, Xu X, et al. Safety and immunogenicity of the BNT162b2 vaccine coadministered with seasonal inactivated influenza vaccine in adults. Infect Dis Ther. 2023 Sep 12;12:2241–2258.

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Footnote 55

Naficy A, Kuxhausen A, Pirrotta P, Leav B, Miller J, Anteyi K, et al. No immunological interference or safety concerns when adjuvanted recombinant zoster vaccine is coadministered with a Coronavirus disease 2019 mRNA-1273 booster vaccine in adults aged 50 years and older: a randomized trial. Clin Infect Dis. 2023 Nov 11;77(9):1238-46.

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Footnote 56

Ramsay JA, Jones M, Vande More AM, Hunt SL, Williams PCM, Messer M, et al. A single blinded, phase IV, adaptive randomised control trial to evaluate the safety of coadministration of seasonal influenza and COVID-19 vaccines (The FluVID study). Vaccine. 2023 Nov 22;41(48):7250-8.

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Footnote 57

Raw R, Rees J, Chadwick D. Increased adverse events following third dose of BNT162b2/Pfizer vaccine in those with previous COVID-19, but not with concurrent influenza vaccine. medRxiv. 2023 Feb 17.

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Footnote 58

Venuto R, Giunta I, Cortese R, Denaro F, Pantò G, Privitera A, et al. The importance of COVID-19/influenza vaccines co-administration: an essential public health tool. Infect Dis Rep. 2022 Dec 05;14(6):987-95.

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Footnote 59

Xu S, Lina SS, Hong V, Kimberly JH, Qian L, Farrington P, et al. Ischemic stroke after bivalent COVID-19 vaccination: A self-controlled case series study. medRxiv. 2023 Oct 15:2023.10.12.23296968.

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Footnote 60

Walter E. Safety of simultaneous versus sequential administration of mRNA COVID-19 and quadrivalent inactivated influenza (IIV4) vaccines: a randomized placebo controlled trial [slides presented at Advisory Committee on Immunization Practices (ACIP) meeting October 25, 2023] [Internet]. U.S.: Duke Human Vaccine Institute; 2023 Oct 25 [cited 2024 Apr 10]. Available from:

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Footnote 61

Public Health Agency of Canada (PHAC). Adverse events following immunization following co-administration of COVID-19 vaccines and other vaccines compared to COVID-19 vaccines alone, Canada. December 1, 2020 – September 15, 2023 [internal report]. Ottawa (ON): PHAC; 2023 Sep 19.

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Footnote 62

Institut national de santé publique du Québec. Accidents vasculaires cérébraux suivant l'administration d'un vaccin contre la COVID-19 [Internet]. QC: Government of Quebec: Institut national de santé publique du Québec; 2023 Aug [cited 2024 Apr 10]. Available from:

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Footnote 63

Matsumoto N, Shimizu J, Yokoyama Y, Tsukahara H, Yorifuji T. Adverse reactions in young children receiving the coronavirus disease 2019 vaccine. Pediatr Int. 2023 Nov 15;65(1):e15696.

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Footnote 64

Aydillo T, Balsera-Manzanero M, Rojo-Fernandez A, Escalera A, Salamanca-Rivera C, Pachón J, et al. Concomitant administration of seasonal Influenza and COVID-19 mRNA vaccines. Emerging Microbes & Infections. 2024 Jan 18;13(1):2292068.

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Footnote 65

Malin JJ, Suárez I, Biehl LM, Schommers P, Knops E, Di Cristanziano V, et al. Immune response to mRNA-based COVID-19 booster vaccination in people living with HIV. HIV Med. 2023 Mar 08;24(7):785-93.

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Footnote 66

Barouch SE, Chicz TM, Blanc R, Barbati DR, Parker LJ, Tong X, et al. Concurrent administration of COVID-19 and influenza vaccines enhances Spike-specific antibody responses. bioRxiv. 2023 Sep 12:2023.09.12.557347.

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Footnote 67

Moss S, Jurkowicz M, Nemet I, Atari N, Kliker L, Abd-Elkader B, et al. Immunogenicity of co-administered Omicron BA.4/BA.5 bivalent COVID-19 and quadrivalent seasonal influenza vaccines in Israel during the 2022-2023 winter season. Vaccines (Basel). 2023 Oct 22;11(10):1624.

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Footnote 68

McGrath LJ, Malhotra D, Miles AC, Welch VL, Di Fusco M, Surinach A, et al. Estimated effectiveness of coadministration of the BNT162b2 BA.4/5 COVID-19 vaccine with influenza vaccine. JAMA Netw Open. 2023 Nov 01;6(11):e2342151.

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Footnote 69

Shimabukuro T. mRNA COVID-19 bivalent booster vaccine safety update [slides presented at Advisory Committee on Immunization Practices (ACIP) meeting April 19, 2023] [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2023 Apr 19 [cited 2023 May 25]. Available from:

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Footnote 70

Shimabukuro T. Update on COVID-19 and influenza vaccine safety [slides presented at Advisory Committee on Immunization Practices (ACIP) meeting October 25, 2023] [Internet]. U.S.: Centers for Disease Control and Prevention; 2023 Oct 25 [cited 2024 Apr 10]. Available from:

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Footnote 71

Public Health Agency of Canada (PHAC). Ischemic stroke and transient ischemic attack following mRNA bivalent COVID-19 vaccination, Canada. December 1, 2020 – October 27, 2023 [internal report]. Ottawa (ON): PHAC; 2023 Nov 14.

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Footnote 72

Public Health Agency of Canada (PHAC). COVID-19 vaccination: Vaccination coverage. Data cut-off 2024 Feb 25 [Internet]. Ottawa (ON): Government of Canada; 2024 Feb 25 [cited 2024 Apr 11]. Available from:

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Footnote 73

Link-Gelles Ruth. Vaccine effectiveness of updated (2023-2024) COVID-19 vaccines [slides presented at Advisory Committee on Immunization Practices meeting on February 28, 2024] [Internet]. U.S.: Centers for Disease Control and Prevention; 2024 Feb [cited 2024 Mar 26]. Available from:

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Footnote 74

Public Health Agency of Canada (PHAC). COVID-19 vaccination: Doses administered. Data cut-off 2023 Dec 03 [Internet]. Ottawa (ON): Government of Canada; 2023 Dec 08 [cited 2024 Feb 27]. Available from:

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Footnote 75

Therapeutic Goods Administration (TGA). COVID-19 vaccine safety report - 29-06-2023. Data cut-off 2023 Jun 25 [Internet]. Woden, ACT: TGA; c2024. Nuvaxovid (Novavax) vaccine; 2023 Jun 29 [cited 2024 Feb 07]. Available from:

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Footnote 76

Immunization Management Division (예방접종 관리과). [COVID-19 Vaccination Adverse Event Status Report (Week 134)] [Internet].: Korea Disease Control and Prevention Agency; 2023 Oct 04 [cited 2024 Mar 01]. Available from:

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Footnote 77

Public Health Agency of Canada (PHAC). Reported side effects following COVID-19 vaccination in Canada. Data cut-off 2024 Jan 05 [Internet]. Ottawa (ON): Government of Canada; c2024. Adverse events of special interest, safety signals, and deaths; 2024 Jan 19 [cited 2024 Feb 13]. Available from:

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Footnote 78

Moderna Biopharma Canada Corp. Product monograph including patient medication information: Spikevax XBB.1.5 [Internet]. Toronto (ON): Moderna Biopharma Canada Corp.; 2023 Sep 12 [cited 2024 Apr 02]. Available from:

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Footnote 79

BioNTech Manufacturing. Product monograph including patient medication information: COMIRNATY Omicron XBB.1.5 [Internet]. Mainz (RP): BioNTech Manufacturing; 2023 Sep 28 [cited 2024 Apr 02]. Available from:

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Footnote 80

Novavax Inc. Product monograph including patient medication information Nuvaxovid™ XBB.1.5 [Internet]. Gaithersburg (MD): Novavax, Inc; 2023 Dec 05 [cited 2024 Mar 01]. Available from:

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