SAINT JOHN, N.B. -- Dr. Robyn MacQuarrie continues to wear a mask and keep a distance of at least two metres from others, even though she is now fully vaccinated against COVID-19.

"I still follow every single public health recommendation," says MacQuarrie, president of Doctors Nova Scotia.

To date, wearing a mask and maintaining physical distance remains the advice of public health officials across Canada regardless of vaccination status.

Dr. Theresa Tam, Canada's Chief Public Health Officer, says public health advice will "evolve" as more people become vaccinated.

Until the directive changes, Dr. MacQuarrie says there's still a risk or virus transmission.

"There's no guarantee," she says.

MacQuarrie says the vaccines are meant to limit COVID-19 infections and prevent any infections from becoming severe.

"What we're doing with the vaccine is trying to limit people from becoming very seriously ill or dying from COVID," she says.

All four of the vaccines authorized for use in Canada begin to offer protection against COVID-19 once administered, however the levels of protection takes time to develop and differs by manufacturer.

"The total protection doesn't come until you're fully vaccinated, until society itself is up to about 70 to 80 per cent, where we get close to that 'herd immunity,'" says Dr. Jeff Steeves, president of the New Brunswick Medical Society.

"So, until then, we're still going to have to separate, wear masks," he says.

Of the four vaccines authorized for use in Canada, three require a second dose (Pfizer, Moderna, and AstraZeneca).

Getting people to show up for the second dose may be a challenge.

As many as five million people in the United States, or eight per cent of the U.S. population who have received a first shot of Pfizer or Moderna, haven't shown up for their second shot according to data from the U.S. Centers for Disease Control and Prevention.

"The job's not done after the first shot and we'll have to keep putting that message out," says Steeves. "Given that we're still working on the first shot, that's a message that we'll be emphasizing more one to three months in the future."