OTTAWA -- Amid a push to have as much of the Canadian population vaccinated as quickly as possible, the federal public health agency says it doesn鈥檛 know how many Canadians have received COVID-19 vaccines in other countries.

With some Canadians opting to travel to another country to receive COVID-19 vaccines potentially earlier than they would be able to at home, in addition to the numerous Canadian citizens who are currently living abroad, the absence of this data means that an important piece of Canada鈥檚 overall vaccination picture is missing, say critics.

CTVNews.ca asked the Public Health Agency of Canada (PHAC) a series of questions related to whether the federal government was keeping track of the number of Canadian citizens who have received COVID-19 vaccines in other countries, and whether that data is informing federal government鈥檚 target of having every willing and eligible Canadian fully vaccinated by the end of September.

In response, PHAC spokesperson Tammy Jarbeau said in a statement that vaccines received by Canadians in other countries are 鈥渃aptured by provincial and territorial immunization registries only if vaccinated individuals voluntarily submit their proof of vaccination to the public health authorities of their province or territory of residence.鈥

Jarbeau went on to say that because PHAC鈥檚 data is based on the provincial and territorial databases, 鈥渢he agency is not able to track鈥 vaccines obtained by Canadians in the U.S., or other countries.

In an interview with CTVNews.ca, NDP MP and health critic Don Davies called the situation 鈥渟hocking,鈥 given that Canada is now well into the second year of the COVID-19 pandemic and a solution has not been found to 鈥減lug this very important hole鈥 in public health data.

Citing the March 2021 Auditor General report that noted poor collaboration and data sharing between federal and provincial governments, among other shortcomings within PHAC in the early months of the pandemic, Davies said not knowing who has been vaccinated in another country is 鈥渋ncomprehensible.鈥

鈥淕etting it right now鈥 is vitally important, and trying to get it later is like trying to put toothpaste back in the tube. You'll never get it all back in,鈥 he said.

As has been reported over the last several months, some Canadians have been travelling to the United States to receive COVID-19 vaccines, whether during their winter stays as snowbirds, or as what some have described as 鈥渧accine tourism.鈥

Davies suggested that the federal government should start asking Canadians who are returning from abroad whether they received a COVID-19 vaccine while out of the country and feed that information directly to PHAC.

鈥淗ow can the federal government let people get through that border, only to voluntarily perhaps [have people] disclose to provinces, and then seek the information later from the provinces? I don't know what's worse, the flabbergasting inefficiency of it, or the sloppy public health inadequacy,鈥 Davies said.

It鈥檚 unclear currently how many Canadians are living or working outside of Canada, with the most recent statistic pegging the total at approximately 2.8 million Canadians, according to the Canadian Expat Association.

Without a sense of how many Canadian citizens who have either been partially, or completely vaccinated in another country but have since returned to Canada, it may also have implications for capturing what the overall degree of herd immunity there is within the country.

For example, PHAC has previously pegged overall vaccination rates to when public health measures may begin to be lifted. As part of April 23 modelling, Chief Public Health Officer Dr. Theresa Tam projected that should 75 per cent of adults have their first dose, and 20 per cent have their second, restrictions could be lifted without maxing out hospital capacity. 

In addition to the economic argument of informing reopening, Davies said there are also regional epidemiological reasons for why it would be helpful to know who has been vaccinated, what kind of vaccine they received, and should there be any issues, what batch their shot was from.

It may also complicate the federal government鈥檚 plans to issue some form of standardized proof of vaccination for Canadians to be able to travel abroad in the future, said Conservative MP and health critic Michelle Rempel Garner.

鈥淭he overall lack of our ability to track and to get Canadians proof of vaccination, I think is going to be a challenge on several fronts,鈥 she said in an interview with CTVNews.ca.

Rempel Garner said that anecdotally she鈥檚 fielded questions from people about what happens if they receive one shot in one country and how they go about receiving their second shot elsewhere.

鈥淓very MP is getting questions on this, particularly from snowbirds and people who have鈥 traveled abroad for a period of time, and have had access to a vaccine in another country鈥 and the federal government should have a response.鈥 Rempel Garner said

CTVNews.ca has reached out to Health Minister Patty Hajdu鈥檚 office for comment and to seek more information about what the government鈥檚 plan is to ascertain how many Canadians have received COVID-19 vaccines in another country.

To-date across Canada, nearly 15 million people have received their first dose of a COVID-19 vaccine, though just 1.2 million people have been fully vaccinated.