OTTAWA -- Shooting down some of the optimism around a COVID-19 vaccine being discovered spelling the end of the pandemic, Canada’s Chief Public Health Officer Dr. Theresa Tam says that vaccine or not, health officials are preparing to deal with the presence of the novel coronavirus and prevention of further spread for years to come.

While some heads of major pharmaceutical companies have said a vaccine could be ready before the end of the year, other experts have cautioned that even 2021 may be an unrealistic timetable.

Now, Canada’s leading health officials are saying even that estimate may be too optimistic.

“We're planning, as a public health community, that we're going to have to manage this pandemic certainly over the next year, but certainly it may be planning for the longer term on the next two to three years during which the vaccine may play a role. But we don't know yet,” Tam told reporters on Tuesday.

“People might think that if we get a vaccine then everything goes back to normal the way it was before. That's not the case… All of the measures we've put in place now will still have to continue with the new reality for quite some time,” Deputy Chief Public Health Officer Dr. Howard Njoo said.

“Certainly I think that we need to temper people's expectations, thinking that the vaccines can be that silver bullet that will take care of everything, and everything we've done up to now won't be necessary in the future,” said Njoo.

To be approved for use, any potential vaccine must move through a well-established testing process that involves three phases of human trials. The first and second phases focus on monitoring whether the drug produces the desired response from the human immune system. The third phase involves far more test subjects and aims to determine whether the vaccine candidate is actually able to stop the virus from infecting a body.

Several trials have already reached the third stage, and Tam said that while at that stage researchers will be able to characterize the vaccine's effects on the immune system and any potential adverse effects, there will be outstanding questions, including how long the vaccine lasts before a booster shot may be needed, and whether it actually prevents an infection or just mitigates the severity.

Tam said that while an effective vaccine would be a “very important aspect of the response,” it shouldn’t be seen as a way to end the pandemic. She said that regardless, some public health measures, such as hand-washing, will have to continue in the long-run.

There are currently 55 COVID-19 drugs, including vaccine candidates, that are currently being investigated in clinical trials authorized by Health Canada. 

The federal government is funding research and development for various options, as well as for immunity research. 

In a new Angus Reid survey, three in five Canadians who were asked said that they worry about the side effects of a potential COVID-19 vaccine, though half of respondents said they’d get a vaccine as soon as one becomes available. One in three said they would wait and see before going and getting vaccinated, citing side effects as a key concern. 

Those surveyed also acknowledged that life will not go back to normal until people are vaccinated, with the majority saying they don’t expect a vaccine to be available until 2021. One-quarter of respondents were skeptical about a vaccine being effective.

Tam said there is also the question of how quickly there will be enough of an effective vaccine to go around.

“It’s likely that there won't be enough vaccines for the population, as the vaccine rolls out. So there'll be prioritization,” she said.

In anticipation of a vaccine, the federal government has begun procuring the supplies that will be essential for “mass vaccinations”, starting with ordering enough syringes and bandages to vaccinate the majority of the Canadian population, twice.  

With files from CTV News’ Ryan Flanagan