Skip to main content

Main menu

  • Home
  • COVID-19
    • Articles & podcasts
    • Blog posts
    • Collection
    • News
  • Content
    • Current issue
    • Past issues
    • Early releases
    • Collections
    • Sections
    • Blog
    • Infographics & illustrations
    • Podcasts
  • Authors
    • Overview for authors
    • Submission guidelines
    • Submit a manuscript
    • Forms
    • Editorial process
    • Editorial policies
    • Peer review process
    • Publication fees
    • Reprint requests
  • CMA Members
    • Overview for members
    • Earn CPD Credits
    • Print copies of CMAJ
    • Career Ad Discount
  • Subscribers
    • General information
    • View prices
  • Alerts
    • Email alerts
    • RSS
  • JAMC
    • À propos
    • Numéro en cours
    • Archives
    • Sections
    • Abonnement
    • Alertes
    • Trousse média 2021
  • CMAJ JOURNALS
    • CMAJ Open
    • CJS
    • JAMC
    • JPN

User menu

Search

  • Advanced search
CMAJ
  • CMAJ JOURNALS
    • CMAJ Open
    • CJS
    • JAMC
    • JPN
CMAJ

Advanced Search

  • Home
  • COVID-19
    • Articles & podcasts
    • Blog posts
    • Collection
    • News
  • Content
    • Current issue
    • Past issues
    • Early releases
    • Collections
    • Sections
    • Blog
    • Infographics & illustrations
    • Podcasts
  • Authors
    • Overview for authors
    • Submission guidelines
    • Submit a manuscript
    • Forms
    • Editorial process
    • Editorial policies
    • Peer review process
    • Publication fees
    • Reprint requests
  • CMA Members
    • Overview for members
    • Earn CPD Credits
    • Print copies of CMAJ
    • Career Ad Discount
  • Subscribers
    • General information
    • View prices
  • Alerts
    • Email alerts
    • RSS
  • JAMC
    • À propos
    • Numéro en cours
    • Archives
    • Sections
    • Abonnement
    • Alertes
    • Trousse média 2021
  • Visit CMAJ on Facebook
  • Follow CMAJ on Twitter
  • Follow CMAJ on Pinterest
  • Follow CMAJ on Youtube
  • Follow CMAJ on Instagram
News
Open Access

Feds update immunization advice with Moderna vaccine approval

Lauren Vogel
CMAJ January 18, 2021 193 (3) E108-E109; DOI: https://doi.org/10.1503/cmaj.1095914
Lauren Vogel
CMAJ
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Tables
  • Responses
  • Metrics
  • PDF
Loading

Moderna and Pfizer COVID-19 vaccines are similar enough that you can swap them in a pinch, according to guidance from Canada’s National Advisory Committee on Immunization (NACI).

The federal advisory group has updated its recommendations on COVID-19 vaccines to include advice on Moderna’s shot, as well as more detailed information on immunizing people with allergies and other special medical circumstances.

Both the Moderna and Pfizer vaccines use similar mRNA technology, which gives the body genetic instructions to mount an immune response, and both are more than 90% effective after two doses, according to Dr. Caroline Quach of NACI. In a Phase III trial of the Moderna vaccine involving more than 30 000 adults, there were 11 cases of COVID-19 among people who got the vaccine versus 185 among those who did not, and no cases of severe disease versus 30 in the placebo group.

Given a lack of data on the interchangeability of COVID-19 vaccines, NACI recommends that people receive the same vaccine product for both doses. But when that’s not an option, patients who receive the Pfizer vaccine first could finish their series with the Moderna product, or vice versa. “Let’s say you run out of Pfizer’s vaccine because you’ve administered all your doses, or you don’t know what your patient had at first… this eases up the complexity,” says Quach.

Are two doses essential?

After one dose, both vaccines are 80%–90% effective, but that protection may only last four to six weeks until a person gets their second dose. While Quach says that’s “pretty good,” NACI recommends that people complete a two-dose series of either vaccine within 28 days.

The guidance document unpacks ethical considerations for provinces weighing whether they should use their limited supplies of vaccines to give a first dose to as many people as possible right away, or keep half in reserve to ensure that people can get their second dose on time.

According to Quach, “some provinces and territories might want to manage their risk differently,” and will need to consider the risks and benefits of wider, immediate protection versus a slower rollout of potentially longer lasting coverage. “We’re happy to see that one dose is efficacious in the short term, but we don’t know more than that. And we don’t even know how long a two-dose series is going to be efficacious, so there’s still quite a lot of uncertainty and we have to be transparent about it.”

Figure1

National recommendations on COVID-19 immunizations now include guidance on the safety, efficacy and use of both Moderna and Pfizer vaccines.

Image copyright iStock.com/undefined undefined. No standalone file use permitted.

New safety details

Both vaccines are very safe but people who have severe allergies to components of the vaccines or their packaging should not be vaccinated. So far, the United Kingdom and United States have documented a handful of severe allergic reactions to the Pfizer vaccine. According to Quach, the key allergen in such cases appears to be polyethylene glycol — a stabilizing ingredient in both the Pfizer and Moderna vaccines that’s also used in laxatives, cough syrup, cosmetics and some foods.

However, other people with allergies unrelated to the vaccine packaging or components can safely receive the shots. For example, “being allergic to peanuts is not a risk factor,” Quach says. Even if someone does experience an unexpected allergic reaction, the risk of serious harm is low because vaccinations are happening in medical settings where those reactions can be treated immediately, she explains.

Although long-term safety data for the Moderna and Pfizer COVID-19 vaccines are still pending, complications from immunizations typically develop “within four to six weeks,” Quach notes. “We have 14 weeks of follow-up” supporting the safety of the vaccines.

Most people who get the Moderna or Pfizer vaccine will feel some discomfort for one or two days afterwards, which may include “feeling tired, having some pain at the injection site, having a little bit of fever,” Quach explains. “You’re going to feel it, but it’s normal and benign to moderate. You don’t have to stay in bed for it.”

Pregnancy and autoimmune issues

NACI also updated their guidance for people who are pregnant or breastfeeding, and people who are immunosupressed or have autoimmune diseases. “Some people have decided not to give the [Pfizer] vaccine to these populations because we said it shouldn’t be administered routinely. But it’s still available on a case by case basis,” Quach says.

In the case of pregnant women, NACI has advised against routine vaccination because there is a “complete absence of data” until vaccine trial participants who were pregnant deliver their babies, Quach explains.

However, if a clinician thinks that a pregnant patient would benefit from vaccination against COVID-19 — for example, if she has a high risk of exposure or complications — “you’re absolutely able to recommend it,” she says. “We don’t think there’s any particular problem, but we need data before saying it’s a strong recommendation.”

Likewise, people whose immune systems are suppressed should be considered for COVID-19 vaccines on a case by case basis, pending further evidence. According to Quach, NACI’s main concern isn’t safety, but that the vaccines won’t work for people who are immunocompromised.

There’s also a possibility that mRNA technologies may exacerbate inflammation and existing autoimmune disease. NACI’s guidance document notes two cases of autoimmune diseases among a total of seven severe adverse events linked to the Moderna vaccine, both in patients with hypothyroidism. While the benefits of vaccination may outweigh the “theoretical risk” for some patients with existing autoimmune issues, “we need to monitor and make sure that’s not a real risk,” Quach says.

Footnotes

  • Posted on cmajnews.com on December 23, 2020

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY-NC-ND 4.0) licence, which permits use, distribution and reproduction in any medium, provided that the original publication is properly cited, the use is noncommercial (i.e., research or educational use), and no modifications or adaptations are made. See: https://creativecommons.org/licenses/by-nc-nd/4.0/

PreviousNext
Back to top

In this issue

Canadian Medical Association Journal: 193 (3)
CMAJ
Vol. 193, Issue 3
18 Jan 2021
  • Table of Contents
  • Index by author

Article tools

Print
Download PDF
Article Alerts
To sign up for email alerts or to access your current email alerts, enter your email address below:
Email Article

Thank you for your interest in spreading the word on CMAJ.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Feds update immunization advice with Moderna vaccine approval
(Your Name) has sent you a message from CMAJ
(Your Name) thought you would like to see the CMAJ web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Feds update immunization advice with Moderna vaccine approval
Lauren Vogel
CMAJ Jan 2021, 193 (3) E108-E109; DOI: 10.1503/cmaj.1095914

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
‍ Request Permissions
Share
Feds update immunization advice with Moderna vaccine approval
Lauren Vogel
CMAJ Jan 2021, 193 (3) E108-E109; DOI: 10.1503/cmaj.1095914
Digg logo Reddit logo Twitter logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • Are two doses essential?
    • New safety details
    • Pregnancy and autoimmune issues
    • Footnotes
  • Figures & Tables
  • Responses
  • Metrics
  • PDF

Related Articles

  • No related articles found.
  • PubMed
  • Google Scholar

Cited By...

  • No citing articles found.
  • Google Scholar

More in this TOC Section

  • New national consortium to tackle anti-Indigenous racism in medical education
  • Unpacking “long COVID”
  • Health advocates want help handling online harassment
Show more News

Similar Articles

Content

  • Current issue
  • Past issues
  • Collections
  • Sections
  • Blog
  • Podcasts
  • Alerts
  • RSS
  • Early releases

Information for

  • Advertisers
  • Authors
  • Reviewers
  • CMA Members
  • Media
  • Reprint requests
  • Subscribers

About

  • General Information
  • Journal staff
  • Editorial Board
  • Governance Council
  • Journal Oversight
  • Careers
  • Contact
  • Copyright and Permissions

Copyright 2021, Joule Inc. or its licensors. All rights reserved. ISSN 1488-2329 (e) 0820-3946 (p)

All editorial matter in CMAJ represents the opinions of the authors and not necessarily those of the Canadian Medical Association or its subsidiaries.

To receive any of the resources on this site in an accessible format, please contact us at cmajgroup@cmaj.ca.

Powered by HighWire