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Ask a Librarian - COVID-19 vaccines

Last updated: February 7, 2022 - Originally published: March 2, 2021

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The Ask a Librarian team is committed to curating free evidence-based resources related to the current COVID-19 pandemic. We continue to update the Ask a Librarian: COVID-19 post and Ask a Librarian: Post-COVID-19 condition (long COVID) post with current clinical summaries, article collections, guidance and more. 

Here we focus on information sources specific to COVID-19 vaccines and the immunization roll-out.

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Clinical summaries


(Included with membership. Access now)  - COVID-19 (Novel Coronavirus) - see Prevention and Screening Immunization section. Updated January 26, 2022.

Recent selected updates

25 Jan 2022: 2-dose vaccination with Pfizer-BioNTech (BNT162b2) associated with greater reduction in transmission of Delta (B.1.617.2) variant compared to 2-dose vaccination with ChAdOx1 nCoV-19 (Oxford-AstraZeneca) (N Engl J Med 2022 Jan 5 early online) View in topic

25 Jan 2022: 3 doses of Pfizer-BioNTech (BNT162b2) vaccine associated with reduced SARS-CoV-2 infection compared to 2 doses in healthcare workers with immunocompetence (JAMA 2022 Jan 10 early online) View in topic

25 Jan 2022: effectiveness of 2 doses of mRNA-1273 (Moderna) vaccine decreased from 2 months after first dose to 7 months after first dose by about 4% to prevent death, 3% to prevent hospitalization, and 16% to prevent asymptomatic or symptomatic SARS-CoV-2 infection in North Carolina, United States during December 2020 to September 2021 (N Engl J Med 2022 Jan 12 early online) View in topic

25 Jan 2022: effectiveness of 2 doses of BNT162b2 (Pfizer-BioNTech) vaccine decreased from 2 months after first dose to 7 months after first dose by about 8% to prevent death, 7% to prevent hospitalization, and 28% to prevent asymptomatic or symptomatic SARS-CoV-2 infection in North Carolina, United States during December 2020 to September 2021 (N Engl J Med 2022 Jan 12 early online) View in topic

25 Jan 2022: effectiveness of 2 doses of BNT162b2 (Pfizer-BioNTech) vaccine against Delta variant decreased from 2-9 weeks after second dose to ≥ 20 weeks after second dose by about 6% to prevent death, 7% to prevent hospitalization, and 24% to prevent COVID-19 in United Kingdom (N Engl J Med 2022 Jan 12 early online) View in topic

25 Jan 2022: previous 2-dose vaccination with Pfizer-BioNTech (BNT162b2) of persons with SARS-CoV-2 infection associated with 68% reduction in transmission of Alpha (B.1.1.7) variant and 50% reduction in transmission of Delta (B.1.617.2) variant (N Engl J Med 2022 Jan 5 early online) View in topic

18 Jan 2022: effectiveness of mRNA vaccines against COVID-19 decreased about 20% from May to August 2021 in New York, United States, during period of increase in B.1.617.2 (Delta) variant prevalence, but effectiveness against COVID-19 hospitalization appears to have remained mostly stable (N Engl J Med 2022 Jan 13) View in topic

18 Jan 2022: increasing time since second dose of ChAdOx1 nCoV-19 (Oxford-AstraZeneca) vaccine associated with increasing rates of severe COVID-19 regardless of dominance of B.1.617.2 (Delta) variant (Lancet 2022 Jan 1) View in topic



(Included with membership. Access now) – Search “COVID-19” to access drug monographs and patient drug information for AstraZeneca, Janssen, Moderna, and Pfizer-BioNTech. 


BMJ Best Practice

Coronavirus Disease (COVID-19). See “Vaccines”. Updated January 14, 2022.



Coronavirus disease 2019 (COVID-19): Vaccines to prevent SARS-CoV-2 infection. Literature review current through December 2021. Updated: January 21, 2022.


Clinical information hubs and toolkits *

Center for Effective Practice - CEP Providers | COVID-19 Vaccines

Elsevier - COVID-19 Healthcare Hub: Vaccines Toolkit

* Immunize Canada - CARD™ - (C - Comfort, A - Ask, R - Relax, D - Distract)

Public Health Agency of Canada - Tool Kit for Health Care Providers 

* University of British Columbia - COVID-19 Immunization Toolkit for Primary Care Offices in Canada


Evidence reviews

American Family Physician

Coronavirus Disease 2019 (COVID-19) Daily Research Briefs

Selected updates

December 27, 2021, Research Update - Vaccination Plus Booster Essential in Preventing Symptomatic Infection from Omicron Variant. Written by John Hickner, MD, MS, on December 14, 2021. (Source: Andrews N, Stowe J, Kirsebom F, et al. Effectiveness of COVID-19 vaccines against the Omicron (B.1.1.529) variant of concern [medRxiv preprint, not peer-reviewed, December 14, 2021].)

November 3, 2021, Research Update - High Effectiveness of BNT162b2 mRNA Vaccine against COVID-19 Hospitalizations up to Six Months after Completing Primary Series. Written by Henry C. Barry, MD, MS, on October 5, 2021. (Source: Tartof SY, Slezak JM, Fischer H, et al. Effectiveness of mRNA BNT162b2 COVID-19 vaccine up to 6 months in a large integrated health system in the USA: a retrospective cohort study. Lancet. 2021;398(10309):1407-1416.)

November 1, 2021, Research Update - Third Pfizer Vaccine Dose Significantly Increases Protection Against Mild and Severe COVID-19. Written by Mark H. Ebell, MD, MS, on September 27, 2021. (Source: Bar-On YM, Goldberg Y, Mandel M, et al. Protection of BNT162b2 vaccine booster against Covid-19 in Israel. N Engl J Med. 2021;385:1393-1400.)


McMaster University

COVID-19 Evidence Alerts – weekly update of high-quality clinical studies with free email notifications

Recent selected reviews

Immunogenicity and Reactogenicity of Vaccine Boosters after Ad26.COV2.S Priming. Sablerolles RSG, Rietdijk WJR, Goorhuis A, et al.  N Engl J Med. Reviewed January 25, 2022.

Additional heterologous versus homologous booster vaccination in immunosuppressed patients without SARS-CoV-2 antibody seroconversion after primary mRNA vaccination: a randomised controlled trial. Bonelli M, Mrak D, Tobudic S, et al.  Ann Rheum Dis. Reviewed January 19, 2022.

Immunological and clinical efficacy of COVID-19 vaccines in immunocompromised populations: a systematic review. Galmiche S, Luong Nguyen LB, Tartour E, et al.  Clin Microbiol Infect. Reviewed January 19, 2022.

Final efficacy analysis, interim safety analysis, and immunogenicity of a single dose of recombinant novel coronavirus vaccine (adenovirus type 5 vector) in adults 18 years and older: an international, multicentre, randomised, double-blinded, placebo-controlled phase 3 trial. Halperin SA, Ye L, MacKinnon-Cameron D, et al.  Lancet. Reviewed January 14, 2022.


Primer AI - COVID-19 primer

Vaccine & Therapeutics  – dashboard for latest research and trending news and articles on vaccines


Veterans Affairs (VA) Evidence Synthesis Program

COVID-19 Evidence Reviews

Recent reviews

Strategies that Promote Equity in COVID-19 Vaccine Uptake for Undocumented Immigrants: A Review. Demeke J, McFadden SM, Dada D, et al. | J Community Health

Aim: To review the evidence on the effectiveness of intervention strategies to increase COVID-19 vaccine uptake among documented and undocumented immigrants.

Effectiveness of COVID-19 Vaccines against Delta (B.1.617.2) Variant: A Systematic Review and Meta-Analysis of Clinical Studies. Pormohammad A, Zarei M, Ghorbani S, et al. | Vaccines

Aim: To address the knowledge gap of vaccine effectiveness (VE) towards the SARS-CoV-2 Delta variant.

Global COVID-19 Vaccine Acceptance: A Systematic Review of Associated Social and Behavioral Factors. Shakeel CS, Mujeeb AA, Mirza MS, et al. | Vaccines.

Aim: To examine how and why the rates of COVID-19 vaccine acceptance and hesitancy differ across countries and continents.

Lymphadenopathy Post-COVID-19 Vaccination with Increased FDG Uptake May Be Falsely Attributed to Oncological Disorders: A Systematic Review. Bshesh K, Khan W, Vattoth AL, et al. | J Med Virol

Aim: To review the evidence on events of lymphadenopathy reported post-COVID-19 vaccination and the recommendations to avoid any clinical and/or diagnostic complications.

SARS-CoV-2 mRNA Vaccine Breakthrough Infections in Fully Vaccinated Healthcare Personnel: A Systematic Review. Ledda C, Costantino C, Motta G, et al. | Trop Med Infect Dis

Aim: To provide evidence on mRNA reported vaccine breakthrough infections among HCP.

Vaccines to prevent COVID-19: A living systematic review with Trial Sequential Analysis and network meta-analysis of randomized clinical trials. Korang SK, von Rohden E, Veroniki AA, et al. | PLoS One

Aim: To assess the effectiveness and safety of COVID-19 vaccines through analyses of all currently available randomized clinical trials.


Articles and article collections *

CMAJ's COVID-19 articles

Cases: Shoulder injury related to SARS-CoV-2 vaccine administration. Jacky C.K. Chow, Sarah L. Koles and Aaron J. Bois. CMAJ January 17, 2022 194 (2) E46-E49; DOI:

Five Things to Know About ...: Immediate reactions after mRNA SARS-CoV-2 vaccination. Samira Jeimy, Tiffany Wong and Christine Song. CMAJ December 06, 2021 193 (48) E1842; DOI:

Health Services: SARS-CoV-2 vaccination should be required to practise medicine in Canada

. Andrew D. McRae and Andreas Laupacis. CMAJ November 29, 2021 193 (47) E1816-E1817; DOI:

Cases: Guillain–Barré syndrome after SARS-CoV-2 vaccination in a patient with previous vaccine-associated Guillain–Barré syndrome. Ling Ling, Sean M. Bagshaw and Pierre-Marc Villeneuve. CMAJ November 22, 2021 193 (46) E1766-E1769; DOI:

Cases: Systemic capillary leak syndrome after ChAdOx1 nCOV-19 (Oxford–AstraZeneca) vaccination. Julie Robichaud, Catherine Côté and Fanny Côté. CMAJ August 30, 2021 193 (34) E1341-E1344; DOI:

Increasing SARS-CoV-2 vaccination rates among Black people in Canada. Azza Eissa, Aisha Lofters, Nancy Akor, Cheryl Prescod and Onye Nnorom. CMAJ August 09, 2021 193 (31) E1220-E1221; DOI:

Clinical Images: Bacillus Calmette–Guérin scar flare after an mRNA SARS-CoV-2 vaccine

. Darren Wan-Teck Lim, Dorothy Hui Lin Ng and Jenny Guek-Hong Low. CMAJ August 03, 2021 193 (30) E1178; DOI:  

See links to additional articles and article collections in our COVID-19 post


Vaccine trials, monographs and tracking

Epocrates COVID-19 Drug Therapy Trial Updates – links to trials and resources focused on therapeutics.

Government of Canada –  COVID-19 Vaccination Tracker – Real-time reporting of doses administration across Canada. Updated January 28, 2022.

Government of Canada –  COVID-19 vaccines and treatments portal – Information on vaccines and treatments authorized for COVID-19, as well as those currently under review. Updated January 27, 2022.

Government of Canada –  Vaccines and treatments for COVID-19 – progress, clinical trials, rollout and safety. Updated December 3, 2021.

Health Canada –  Approved COVID-19 Vaccines - Information on COVID-19 vaccines including authorized vaccines, types of vaccines and on-going safety monitoring. Updated January 7, 2022.

*Lexicomp –  COVID-19 mRNA vaccines: Drug information.

Lexicomp – Lexi-Drugs Coronavirus Disease 2019 Vaccine Tracker (includes links to trials).

Milken Institute – COVID-19 Treatment and Vaccine Tracker – Updated January 27, 2022.

* National Library of Medicine – – COVID-19 vaccine trials

Regulatory Affairs Professional Society (US) - COVID-19 vaccine tracker

* World Health Organization - COVID-19 vaccine tracker and landscape


Guidelines and other information


Centers for Disease Control and Prevention – Different COVID-19 Vaccines. Updated January 21, 2022.

International Coalition of Medicines Regulatory Authorities (ICMRA) - “expedite and streamline the development, authorization and availability of COVID-19 treatments and vaccines worldwide.”

World Health Organization – Coronavirus disease (COVID-19): Vaccines Q&A Updated January 20, 2022.

 World Health Organization - COVID-19 vaccines. No date.



*CMA Joule - CPG Infobase: Clinical Practice Guidelines on COVID-19 Vaccines. Updated January 28, 2022.

Immunize Canada - COVID-19 Information for Health Care Providers. No date.

Indigenous Services Canada – COVID-19 vaccines and Indigenous peoples. Updated January 27, 2022.

*National Advisory Committee on Immunization (NACI): Statements and publications – COVID-19. Updated January 28, 2022.

*Public Health Agency of Canada - COVID-19 vaccine: Canadian Immunization Guide – Updated January 28, 2022.

Public Health Agency of Canada – Vaccines and treatments for COVID-19: Canada’s Vaccine supply. Updated January 27, 2022.



British Columbia

BC Centre for Disease Control – COVID-19 vaccination at a glance. No date.

Doctors of BC –-COVID-19 Vaccine Office Toolkit No date.

Government of British Columbia - COVID-19 Immunization Plan. Updated January 28, 2022.

Immunize BC - COVID-19 Vaccine Frequently Asked Questions. Updated January 24, 2022.


Government of Yukon – COVID-19 Vaccine – vaccine schedule and appointment booking, vaccine strategy and rollout schedule. No date.

Northwest Territories

Government of the Northwest Territories - COVID-19 Vaccine – includes vaccine information in multiple languages. Updated January 28, 2022.


Government of Alberta - COVID-19 vaccines and records. Updated January 27, 2022.

Alberta Health Services – COVID-19 & Influenza Immunization Booking. Updated January 26, 2022.


Government of Saskatchewan - COVID-19 Vaccine - delivery strategy, vaccine information, and information for health care workers. No date.


Province of Manitoba – COVID-19 Vaccine – includes Q &As, Information for Health Professionals, and eligibility criteria. Updated January 28, 2022.


Nunavut Department of Health - COVID-19 Vaccination – includes vaccine information, rollout and FAQs. Updated January 25, 2022.


Government of Ontario - COVID-19 vaccines for Ontario – vaccination status, safety and rollout. Updated January 30, 2022.

Ontario College of Family Physicians - COVID-19 Vaccines | Vaccinating – curated list of provincial and federal vaccine information. No date.

* Ontario COVID-19 Science Advisory Table – Dashboard - Current COVID-19 Risk in Ontario by Vaccination Status. No date.

Public Health Ontario - COVID-19 Vaccines. Updated January 28, 2022.


Government of Quebec -  COVID-19 vaccination campaign. Updated December 15, 2021.

New Brunswick

Government of New Brunswick – COVID-19 Vaccines – development, rollout and information for health professionals. Updated January 29, 2022.

Nova Scotia

Government of Nova Scotia - Coronavirus (COVID-19): vaccine – includes immunization plan, supply and distribution, and vaccine data. No date.

Nova Scotia Health - COVID-19 Vaccine – vaccine information and distribution plan. No date.

Prince Edward Island

Government of Prince Edward Island -  COVID-19 Vaccines and Immunization Phased Approach – vaccination status, rollout schedule, and safety. Updated November 23, 2021.

Government of Prince Edward Island – COVID-19 Vaccine Information for Health Care Providers – Updated November 16, 2021.

Government of Prince Edward Island - Getting the COVID-19 Vaccine – January 24, 2022.


Government of Newfoundland and Labrador – COVID-19 Immunization Plan for Newfoundland and Labrador – vaccine information, administration and resources for health care professionals. No date.


Ethics and medical-legal resources

Canadian Medical Protective Association (CMPA) – Vaccination - “As the COVID-19 vaccination rollout expands, there are a number of medical-legal considerations physicians will want to be aware of.” Updated January 10, 2022.

Johns Hopkins Berman Institute of Bioethics - Coronavirus Ethics and Policy Insights and Resources. No Date.

National Collaborating Centre for Healthy Public Policy/ Institut national de santé publique (Québec) – Public Health Ethics and COVID-19: Vaccination – Selected Resources. Updated March 2021.


Webinars and podcasts *

Association of Medical Microbiology and Infectious Disease Canada, Public Health Agency of Canada. COVID-19 vaccine foundations webinar for health care providers

* CanVax / Public Health Agency of Canada - CANVax Presents: PHAC Webinar Series on COVID-19 Vaccines. Updated January 26, 2022.

* CanVax / Immunize Canada - Immunize Canada and CANVax Webinars.

National Collaborating Centre for Infectious Diseases. NCCID hosts the Public Health Agency of Canada COVID-19 vaccine webinars for health care providers


Patient information *

EBSCO - Patient decision aid for Covid-19 Vaccination. Updated January 20, 2022.

Immunize BC -  COVID-19 Vaccine Frequently Asked Questions. Updated January 24, 2022.


MayoClinic - COVID-19 vaccines: Get the facts

Ontario Ministry of Health - Vaccine safety

*  Health Agency of Canada - Vaccines for COVID-19

* ScienceUpFirst - Together Against Misinformation

* UpToDate - Patient education: COVID-19 vaccines (The Basics)


Pre-populated literature searches

Vaccines in PubMed search by the SMHS & EMHS Library and Information Service

Google Scholar Pfizer or Moderna vaccines search by Dean Giustini – Coronavirus Disease 2019 (COVID-19)—For Beginners to Experts - University of British Columbia.


Need more information or have a more focused clinical question on COVID-19 vaccines or any other clinical topic of interest? Contact the Ask a Librarian team to request a literature search.

This material is for informational purposes only. It is not intended to be a substitute for professional medical advice and should not be relied on as health or personal advice. The opinions stated by the authors are made in a personal capacity and do not necessarily reflect those of the Canadian Medical Association and its subsidiaries including Joule.

About the author(s)

CMA Joule’s medical librarians are the professionals behind “Ask a Librarian”, a service for all CMA members looking for clinical search expertise. This experienced team of librarians can support you by searching on your behalf, teaching you effective search strategies or training you to use our clinical resources.