TORONTO -- The availability of booster shots and third doses of COVID-19 vaccines is a hot topic for many Canadians as additional doses are being rolled out for certain populations or those who need to travel for work, depending on their province or territory of residence.

Health experts and federal agencies have been debating the need for booster shots across the general population, saying that a primary vaccine course still provides good protection against COVID-19.

Health Canada regulates drugs and vaccines in this country, while the National Advisory Committee on Immunization (NACI) is the federal entity that provides advice to provinces and territories regarding use of the COVID-19 vaccines.

On Dec. 3, NACI recommended mRNA booster shots be administered to Canadians who are aged 50 and up, residents of long-term care homes for seniors or other congregate living settings that provide care to seniors, those who received two doses of the AstraZeneca or one dose of the Johnson & Johnson vaccines, and adult front-line health-care workers who have direct contact with patients, as well as adults who live in or come from First Nations, Inuit or Metis communities, six months after completing a primary vaccine course.

In addition, NACI says booster doses "may be offered" to people between the ages of 18 and 49 years old.

On Nov. 12, Health Canada approved the use of the Moderna COVID-19 vaccine for booster shots in people aged 18 and up, to be given at least six months after finishing a primary vaccine course. The boosters contain a half-dose of the Moderna vaccine.

Health Canada on Nov. 9 authorized use of the Pfizer-BioNTech COVID-19 vaccine as a booster for all people 18 and older, to be administered at least six months after completing a primary vaccine course. These boosters contain a full dose of the Pfizer vaccine.

In early September, NACI recommended third vaccine doses be administered to certain immunocompromised individuals at least 28 days after their previous dose. Each province and territory has enacted a third-dose policy for immunocompromised people.

Third doses are considered part of a primary vaccine course, while boosters are meant to be given when vaccine effectiveness wanes and often, but not always, contain a smaller dosage.

Public opinion on the matter appears to sway in favour of booster shots. The vast majority of Canadians have expressed interest in one, according to a survey commissioned by CTV News, with 69 per cent of respondents saying they were interested and 15 per cent saying they were somewhat interested.

ELIGIBILITY FOR ADDITIONAL DOSES BY PROVINCE AND TERRITORY

This was updated with the latest booster shot eligibility requirements for all provinces and territories on Dec. 2, 2021.

BRITISH COLUMBIA

Seniors aged 70 and up and Indigenous people aged 18 and up, as well as those who live in rural and remote Indigenous communities, are able to get an mRNA booster shot. Residents of independent living facilities or people who receive long-term home support are also eligible. Health-care workers who received their second dose on or before March 15, can get boosters. Finally, people who received two doses of the AstraZeneca vaccine can schedule a booster shot as well.

Starting in January 2022, everyone aged 18 and up will be invited to get boosters between six and eight months after their primary vaccine course.

People who are moderately to severely immunocompromised may be able get a third dose four weeks after their second one. Booking invites will be sent through the province's Get Vaccinated system.

ALBERTA

On Dec. 1, Alberta announced plans to make booster shots available to those aged 18 and up in stages. Starting Dec. 6, bookings for a third dose will be open to everyone 60 and up who had their second dose six months prior.

Until then, seniors 70 and up or seniors' supportive living residents can get a booster shot six months after their second dose, as well as First Nations, Metis and Inuit people. Health-care workers who provide direct patient care and received their second dose less than eight weeks after their first one can also get a booster six months after their second dose.

Immunocompromised individuals 12 years and older with specific conditions may be eligible for a third dose eight weeks after their second one.

Finally, travellers to places where the AstraZeneca vaccine or mixed doses aren't recognized can get a third shot four weeks after their second dose. People who received two doses of AstraZeneca or one dose of the Johnson & Johnson vaccine can also get an mRNA booster shot six months after their last dose if they haven't already received an additional mRNA dose for travel purposes.

SASKATCHEWAN

People aged 65 years and older, health-care workers and individuals born in 2009 or earlier with certain underlying health conditions, can receive an mRNA booster dose six months following their second dose. Residents of the Far North and those living in First Nations communities who are aged 50 and older may also get boosters. Residents of long-term care, special care and personal care homes can get an additional dose 28 days after their second dose

Some immunocompromised and clinically extremely vulnerable individuals can also receive a third dose 28 days after their second one. Those who are eligible for medical reasons will receive a letter from the ministry of health or their physician.

A third or even fourth dose is also available for those who may require it for international travel.

MANITOBA

Manitoba is allowing all adults 18 and older to receive a COVID-19 booster shot a minimum of six months after a second dose. The province also recommends an additional mRNA vaccine dose for residents of personal care homes or congregate elderly person housing, pregnant people and individuals living north of the 53rd parallel or in a remote community, as well as First Nations, Inuit and Métis people. Manitobans who have only received a viral vector COVID-19 vaccine or one not approved by Health Canada, people who work or live in a congregate living facility and individuals receiving home care or any level of Community Living Disability Service support, as well as health-care workers who have direct contact with patients, personal care home residents or clients, are also recommended to get an additional dose.

A third dose is also recommended for people who may be immunocompromised.

Most people can book a third dose six months after their second one. Manitobans will need a prescription from their doctor to receive an additional dose before the end of the six-month period, whether they're immunocompromised or need one for travel to meet the demands of their destination's health regulators.

ONTARIO

On Dec. 2, Ontario announced starting Dec. 13 residents aged 50 and up can book an appointment for a booster shot six months after their second dose. Eligibility will be expanded further in January based on age and risk.

Currently, boosters are recommended for people over the age of 70 and health-care workers, as well as First Nation, Inuit and Metis adults and their non-Indigenous household members, six months after their second dose. Residents of long-term care homes, retirement homes, elder care lodges or other congregate settings for seniors are also eligible. Individuals who received a complete series of a viral vector vaccine (i.e. two doses of AstraZeneca or one dose of Johnson & Johnson) at least six months ago can also get an mRNA booster shot.

A third dose is recommended for people who may be moderately to severely immunocompromised or receiving dialysis (hemodialysis or peritoneal dialysis) eight weeks after their previous dose.

If being offered an additional Moderna dose, residents of long-term care homes, retirement homes or seniors in other congregate living settings, along with people 70 years of age and older and all eligible immunocompromised individuals, are recommended to receive a full dose of the vaccine. All other individuals, if being offered Moderna, are recommended a half-dose.

Individuals with proof of immunization who underwent a one- or two-dose course of a COVID-19 vaccine not approved by Health Canada may receive an additional mRNA vaccine dose at least 28 days after the preceding one.

Finally, the province is also recommending individuals who received hematopoietic stem cell transplants, hematopoietic cell transplants (autologous or allogeneic) and recipients of CAR-T-cell therapy begin a new primary vaccine course due to the loss of immunity following therapy or transplant.

QUEBEC

An mRNA booster shot is recommended for people aged 70 and up, residents of residential and long-term care centres, people living in private seniors' residences and people living in settings with a high percentage of vulnerable older adults, such as intermediate and family-type resources, as well as certain religious communities, six months after their second dose. People who have undergone a full primary course of the AstraZeneca, including the Covishield version, and the Johnson & Johnson vaccines are also eligible for an additional mRNA dose. A booster is not required for those who have had COVID-19.

Adults on dialysis or with weakened immune systems are recommended a third COVID-19 vaccine dose four weeks after the second dose. The additional dose is necessary even if the individual has had COVID-19.

NEW BRUNSWICK

People aged 65 and up, First Nations individuals, residents of long-term care facilities and school personnel who received their second vaccine dose at least six months ago are able to get a booster shot. Health care workers, including those working in long-term care facilities, are also eligible.

Individuals aged 12 and up who are moderately to severely immunocompromised are able to get a third dose of a COVID-19 vaccine 28 days after their second one. This also applies to people who have received one or two doses of the AstraZeneca or Johnson & Johnson vaccines, regardless of their age.

People who received mixed vaccine doses and must travel outside of North America for work, school or medical procedures can apply for an additional dose but must show their travel is essential.

NOVA SCOTIA

Seniors aged 70 or older are eligible to receive their COVID-19 booster shot. Long-term care home residents who received their second dose at least six months prior are also eligible. Additionally, designated caregivers of long-term care residents and frontline health-care workers who have received two doses, with less than 28 days between them, are eligible for a third shot. Anyone who received two doses of the AstraZeneca vaccine can also book their third dose. Members of First Nations or African Nova Scotian communities who are aged 30 or older can also receive their booster shot.

Moderately or severely immunocompromised people who received two doses of a COVID-19 vaccine can also get a third dose of an mRNA vaccine at least 28 days after they received their last dose.

Those who are required to travel for work and need an extra shot to meet travel or self-isolation requirements in another country can apply for an additional vaccine dose.

PRINCE EDWARD ISLAND

Residents of long-term care and community care facilities, seniors aged 70 and up and Indigenous people, as well as individuals aged 18 and up who received two doses of the AstraZeneca vaccine or one dose of the Johnson and Johnson vaccine, are recommended for an additional dose at least six months after their initial vaccine course. Health-care workers with direct in-person patient contact who received their first two doses within a 28-day period can get a third dose six months after their second one.

Moderately to severely immunocompromised islanders may be able to receive a third dose 28 days after their second one.

Those who must travel for work or school and received mixed vaccine doses may also be eligible to get an additional matching mRNA vaccine dose.

NEWFOUNDLAND AND LABRADOR

People aged 70 and up, adults living in long-term care or other congregate settings that provide care for seniors and adults who are Indigenous or live in an Indigenous community can get an mRNA booster dose six months after completing their primary vaccine course. Individuals who have received either two doses of the AstraZeneca vaccine or one dose of the Johnson & Johnson vaccine, as well as adult frontline health-care workers who have direct contact with patients and were initially vaccinated within a 28-day interval, are also eligible.

Moderately to severely immunocompromised individuals may be eligible to receive a third mRNA vaccine dose four weeks after their second one.

Those who underwent a mixed vaccine course and need to travel for work or a medical procedure outside of Canada or attend school outside of the country are also eligible for an additional dose.

YUKON

Booster shots are available to all residents aged 50 and up and health-care workers six months after their primary vaccine course. Different communities may have clinics open at different times.

Third doses are also available to those who may be immunocompromised as part of their primary vaccine course.

NORTHWEST TERRITORIES

All residents who are or will be 18 years of age by the end of 2021 are eligible for a booster shot six months after their second dose. People who are severely immunocompromised, as well as front-line health-care workers in Yellowknife and Behchoko, are eligible for an additional mRNA vaccine dose.

NUNAVUT

COVID-19 booster shots are available to all residents 12 and up who received their second dose of an approved vaccine more than six months ago. 

With files from CTVNews.ca's Hannah Jackson