How many COVID-19 vaccine doses should you have by now?

Earlier this month, the National Advisory Committee on Immunization (NACI) said people facing a high risk of serious illness should get another COVID-19 booster in the spring.

With the latest messaging aimed at specific groups and COVID-19 cases seemingly stable across the country, many Canadians might be left wondering if or when they should schedule their next booster shot.

Here is a summary of the current COVID-19 vaccination guidelines from NACI, for both children and adults who are at increased risk of serious illness and those who are not.

PRIMARY VACCINE SERIES

Aside from a very small number of people with legitimate medical exemptions, NACI says all Canadians five and older should be immunized against COVID-19 with a full primary vaccine series. The number of doses considered to make up a full series depends on the vaccine and the individual being vaccinated.

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For people of most ages receiving either the Pfizer-BioNTech Comirnaty or Moderna Spikevax vaccine, and who are not moderately or severely immunocompromised, a full series consists of two doses about eight weeks apart.

For children between six months and four years old who are receiving the three-microgram pediatric formulation of the Pfizer-BioNTech Comirnaty vaccine, a full series is three doses, eight weeks apart.

For children six months and older who are receiving the Moderna Spikevax original vaccine, the full series still consists of two doses, eight weeks apart.

NACI's guidance for children aged six months to under five years old is that they "may be immunized with a primary series of an authorized mRNA vaccine," what the organization calls a "discretionary recommendation."

For adults 18 years and older who are receiving the Janssen Jcovden vaccine, a full series is one dose.

What constitutes a full primary vaccine series for moderately- to severely-immunocompromised people looks a little different, with NACI recommending more doses and shorter dose intervals of between four and eight weeks.

Children receiving the three-microgram pediatric formulation of the Pfizer-BioNTech Comirnaty vaccine should receive four doses.

For everyone else who is immunocompromised and is receiving either the Pfizer-BioNTech Comirnaty original vaccine or the Moderna Spikevax original vaccine, a full course is three doses.

A full course of the Novavax Nuvaxovid vaccine or the Medicago Covifenz vaccine is two-to-three doses. A full course of the AstraZeneca Vaxzevria vaccine is two doses, plus one dose of an mRNA vaccine, and a full course of the Janssen Jcovden vaccine is one dose, plus one dose of an mRNA vaccine.

BOOSTER DOSES

Because vaccine protection wanes over time, and because the COVID-19 Omicron variant and its sub-variants continue to circulate in Canada and globally, NACI and Health Canada recommend booster doses six months after the last dose of a primary course for everyone aged five and up.

"It remains important to stay up to date with your COVID-19 vaccines, including recommended booster doses, given the continued circulation of SARS-CoV-2 virus variants in Canada and elsewhere," Dr. Theresa Tam, Canada’s chief public health officer, said in a media release on March 3. "Booster doses help to build back protection against severe disease that wanes over time after COVID-19 vaccination or infections."

Specifically, NACI and Health Canada recommend bivalent Omicron-containing mRNA COVID-19 vaccines as the "preferred booster," for fully-vaccinated people aged five and older.

According to the current Canadian Immunization Guide, regardless of any previous booster doses, fully-vaccinated adults 65 and older should have received one booster doses since the start of fall.

The same recommendation applies to adolescents and adults between 12 and 64 years old who are at increased risk of severe illness from COVID-19, including those who are immunocompromised.

All fully-vaccinated adults between 18 and 64 years old who are not at increased risk of severe illness should have received at least one booster dose since their primary series, as long as it's been six months since their last primary dose. If someone received a booster dose before the start of fall 2022 and it's been at least six months since their last dose, they are now eligible for another booster dose.

Children between five and 11 years old with an underlying medical condition that places them at high risk of severe illness due to COVID-19 should also be boosted, NACI says.

There are no authorized COVID-19 vaccine boosters for children under five years old.