OTTAWA -- Ottawa Medical Officer of Health Dr. Vera Etches says, to date, all cases of COVID-19 in Ottawa are linked to travel, which is why she’s urging social distancing now, to keep community spread low.

Speaking on CTV Morning Live, Dr. Etches said her estimate Sunday of up to 1000 potential cases in the capital was based on several factors.

"I think the media’s picked the highest range," she said. "What we’re seeing is cases two weeks ago were identified just this week because people had traveled two weeks ago, had become infected out of the country, and had come back to Canada. That was at a time when we didn’t have the same kind of messaging to all returning travels to self-isolate. So, we estimate the measures at that time would not have identified every case."

Etches says every case is likely to create two more, and the doubling time can be about five days, which is where she says the estimate of 200 to 1000 potential cases came from.

But she says, to date, there’s been no definitive proof that the virus has spread locally.

"I think we’re still very early. We have not detected cases that prove local transmission," she said. "We have not detected it without travel."

Social distancing measures are meant to limit that local transmission.

"It’s why we are asking people to think about this as if the virus is here and the rationale for social distancing is that we can then stop the transmission of the virus between ourselves," she said. "We're not going to stop all transmission of the virus. What we're doing is we're trying to decrease the rate of transmission. You're not at risk standing beside someone who just traveled if they don't have symptoms. If you're not coughing, and sneezing, and have a fever, you're not as infectious, and not likely to pass that virus on."

On Sunday, Etches recommended residents cease all non-essential travel outside the home, but she says that doesn’t mean the entire city is shutting down.

"My advice here is not to not work. People need to work and people need to carry out functions that keep our city going," she said, but added working from home whenever possible is ideal. "My advice to all employers is if you have the option for your workers to work from home, this is a good time to use that."

For workers who can't stay home, Dr. Etches says the lack of definitive community transmission at this time means the risk is still low, but there are precautions front-line workers and first responders can take.

"Think about universal precautions: imagine that your hands get infected, keep them away from your eyes, nose, and mouth, and clean your hands as soon as you can," she said.

Etches says the next steps are to keep an eye on the number of cases in Ottawa, to monitor whether community transmission is happening, and to evaluate whether the social distancing measures being undertaken have an effect on keeping community transmission low.