Keep Current With COVID-19 Vaccine Boosters

You'll hear more questions about COVID-19 vaccines...since guidance about boosters is continually evolving.

What's the difference between a "booster" and "additional dose"?

"Boosters" aim to maintain protection after an adequate initial immune response. Third or "additional doses" are for patients who likely had an INadequate response to the initial series.

Keep in mind that boosters are given at least 6 months after a completed series...but additional doses are given earlier, at least 4 weeks after a completed series.

Who needs a booster? Expect long-term care residents or seniors living in group settings to qualify for an mRNA COVID-19 booster (Comirnaty or Spikevax) at least 6 months after a completed primary series.

Other patients may qualify for a booster, depending on your provincial rules. For example, Alberta is giving boosters for seniors 75 and older...or First Nations, Métis, and Inuit people 65 and older.

Patients should expect that side effects after a booster will likely be similar to those after the primary series.

Who needs an additional, or third, dose? Patients who have a moderately to severely weakened immune system will be eligible for an additional dose at least 4 weeks after a completed primary series.

Be aware that an mRNA COVID-19 vaccine is preferred for the booster or additional dose...regardless of whether patients had an mRNA or viral vector vaccine (AstraZeneca's Vaxzevria or Johnson & Johnson/Janssen) for their primary series.

What are considerations with side effects? Send worried patients to your pharmacist...to help put concerns into perspective.

For example, the risk of myocarditis, or heart inflammation, is MUCH higher from COVID-19 infection than from vaccination. Plus most postvaccination cases are mild and resolve in a few days.

Continue to focus on promoting COVID-19 vaccines for UNimmunized patients. Get our FAQ, Communicating About COVID-19 Vaccination, to help your pharmacist address concerns...and debunk myths.

And use our COVID-19 Vaccines chart to keep up with emerging details about pediatric vaccines, storage, and more.

Key References

  • https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/statement-september-10-2021-additional-dose-covid-19-vaccine-immunocompromised-following-1-2-dose-series.html?hq_e=el&hq_m=2190151&hq_l=1&hq_v=42f995eed6#a5 (10-28-21)
  • https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/statement-september-28-2021-booster-dose-long-term-care-residents-seniors-living-other-congregate-settings.html#a5 (10-28-21)
  • https://www.alberta.ca/covid19-vaccine.aspx (10-28-21)
  • https://www.canada.ca/en/public-health/news/2021/10/statement-from-the-council-of-chief-medical-officers-of-health-ccmoh-update-on-covid-19-vaccines-and-the-risk-of-myocarditis-and-pericarditis.html (10-28-21)
  • Pharmacy Technician's Letter Canada. November 2021, No. 371101



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