Some experts are warning that Quebec's unprecedented plan to tax adult residents who refuse to be vaccinated against COVID-19 could have the greatest impact on those who have "suffered the most during the pandemic," such as vulnerable and marginalized groups.

Vardit Ravitsky, a professor of bioethics at the Universite de Montreal, told CTV News Channel on Wednesday that her main concern is that the tax will not increase pressure on the unvaccinated to get the jab, but will further certain inequities created by the COVID-19 pandemic.

"From an ethical perspective, we're trying to select public health interventions that are the most equitable and just possible. This... does not respect this principle," Ravitsky said.

In a Canadian first, Quebec Premier François Legault announced on Tuesday that a new "health contribution" will have to be paid by residents who haven't received their first dose of a COVID-19 vaccine for non-medical reasons.

According to data tracked by CTVNews.ca, roughly 10 per cent of Quebec's population is unvaccinated, but provincial data shows they make up nearly half of intensive care beds.

In a statement, the Canadian Civil Liberties Association said the tax plan is deeply troubling, given that the Charter of Rights and Freedoms recognizes individual autonomy over our bodies and medical decisions.

Cara Zwibel, acting general counsel for the association, said in the statement that the tax penalty is a divisive measure that will end up punishing and alienating those who may be most in need of public health supports and services.

Montreal-based lawyer Julius Grey told CTV News Montreal "there is no question" that the tax is a violation of the Charter of Rights and Freedoms, but whether it's upheld in court will be a "close call," he said.

"It’s not a discriminatory tax. It’s a way of trying to force vaccination, and while that is a clear and major Charter violation, I am not certain what the result will be... It could be argued both ways," Grey said.

While the provincial government provided little detail on how the tax would work, Legault said the financial penalty would be a "significant" amount.

If the tax is issued as a flat fee, Ravitsky said it will "definitely impact the most vulnerable in the worst way."

"We know that the most vulnerable and most marginalized communities have suffered the most during the pandemic," she explained. "And so to target the pockets of again the most vulnerable, adding stress to the already existing stress, may actually end up doing more damage from a public health perspective than doing good."

Ravitsky said she doubts that a tax will change the behaviour of "hard-core anti-vaxxers."

"I'm still in favour of incentivizing through public health messages, and honestly, Quebec hasn't used vaccine passports to their full possible extent," she said.

Ravitsky saidd that there are many social and commercial activities that remain open to those who are unvaccinated.

"I think it would be more equitable to increase the pressure to vaccine passports than to target again individual's pockets, when $100, $500 may mean almost nothing for some families and may be an incredible burden for other families," she said.

Legault justified the tax by saying the province needs to "go further" than just mandating vaccine passports to more areas, such as liquor stores and cannabis stores.

Unvaccinated adults "will have a bill to pay because there are consequences on our health-care network and it's not up to all Quebecers to pay for this," the premier said.

While the issue of vaccination is already "extremely polarizing," Ravitsky said it is unfortunate that the issue has been politicized. She added that a vaccine tax will only "exacerbate" this.

"We're seeing this already breaking up families, friendships -- it's really a very difficult moment that we're living as a society," she said. "Implementing a very controversial measure when we still have less controversial measures available to us, such as vaccine passports, seems to be misguided at this point."

With hospitals becoming overwhelmed with COVID-19 cases across the country, the Canadian Medical Association (CMA) says all governments should do whatever they can to boost vaccination rates.

"We've gotten to a point where it has become very difficult to get that final sort of 10 or 15 per cent of people across the finish line," said CMA president Dr. Katharine Smart in an interview with CTV News.

While Quebec's unvaccinated tax would be a first in Canada, other counties around the world have implemented similar measures.

Austria was the first country in Europe to create such a tax. The government announced in November that all residents over the age of 14 will be fined 3,600 euros (CA$5,150) for every three months they remain unvaccinated.

Starting this weekend in Greece, people over 60 will be forced to pay 100 euros (CA$143) for every month they don't get their shots.

Singapore has taken it one step further. The country, which has a universal health system similar to Canada's, announced that as of Jan. 1 unvaccinated residents who end up in hospital with COVID-19 will be billed for their own medical care.

With files from The Canadian Press, and CTV News Montreal's Joe Lofaro and Selena Ross