OTTAWA -- Ottawa's medical officer of health says non-medical masks may serve as an added layer of protection to prevent the wearer from spreading COVID-19 to others, but they are not the only solution to halting the spread of the disease.

Speaking to CTV Morning Live's Leslie Roberts on Tuesday morning, Dr. Vera Etches said there are important distinctions between medical-grade masks and non-medical masks, which can be made at home.

"Medical masks need to be reserved for health care workers and first responders," she said. "For non-medical masks, we've said all along what's important is, if you're sick, you want to make sure you keep your secretions to yourself. Make sure your nose and your mouth are covered when you go out to get health care because that protects others."

Chief Public Health Officer of Canada Dr. Theresa Tam said Monday wearing a cloth mask is a way to help prevent spreading COVID-19 to others. It was a shift in tone about mask use that Tam said came as a result of a growing body of evidence showing asymptomatic and presymptomatic carriers can spread the virus to others.

Etches reiterated that non-medical masks are not very effective in keeping oneself safe.

"There's still not a lot of evidence that if you wear a mask it will protect you from getting sick," Dr. Etches said. "These are non-medical masks that are not fitted the same way as a medical mask but, for those who need to go out to get groceries or prescriptions filled, wearing a mask might protect others."

Dr. Etches said masks are just one tool that can be used and don't mean other precautions shouldn't be taken.

"It's never one solution that's going to help us win this battle against COVID-19. It's important to remember it's on top of physical distancing. You want to make sure you're still two-metres away from everyone else. Homemade masks are not going to be as effective as a medical mask and you still need to have that protection of distance to keep away from the potential for infection."

Dr. Etches said it's not known if greater mask-wearing earlier would have helped limit the spread of infection, but the public health unit's policies are evolving.

"It doesn't hurt to try to add layers of protection," she said. "The evidence is emerging that people who are asymptomatic and people in the two days before they feel sick can actually pass on the virus. We're in an evolving situation and we want our response to evolve to use the best evidence that we have."

Some promising signs, but infections continue to increase

There are 370 laboratory-confirmed cases of COVID-19 in Ottawa, as of Ottawa Public Health's update on Monday. Dr. Etches says the number of cases continues to increase, but there are some signs physical distancing measures are starting to have a positive effect.

"We're seeing that the numbers are not increasing as rapidly as they would be if we didn't have the physical distancing in place," she said. "There are some promising signs that we are starting to see this make a difference. We need to continue because we are still seeing the increase in infections."

However, she cautioned that the total number of confirmed cases is just a part of the bigger picture.

"We're not testing everybody," Dr. Etches said. "We know there's a lot of infection in our community not yet detected, so we need to make sure we take a lot of precaution in interpreting when it might be time to declare victory and carefully go about making sure we don't increase the risk too early."

More outbreaks possible

There are seven institutional outbreaks of COVID-19 in Ottawa. Dr. Etches said it's possible that number will rise.

"We are seeing the numbers increase, along with the numbers of infections increasing in our community," she said. "Unfortunately, this COVID-19 is a difficult virus to tackle precisely because of the way people don't know if they're infected or not, so it's possible that we'll continue to get more outbreaks as we get more cases. We are all working hard to try to turn that curve around and get past that increasing number we see every day."

On Monday, an outbreak was declared at the Montfort Hospital. An outbreak is declared when there is at least one positive case of COVID-19 in a staff member of an institution or in a resident, if the institution is a long-term care home.