Ottawa's top doctor is issuing a strong message to residents, urging them to stay home unless necessary.

The capital's chief medical officer is discouraging all gatherings of people, and recommends that residents stay in their homes unless absolutely necessary, warning that the number of actual cases of COVID-19 in Ottawa is likely much higher than the official count so far.

Since the city's COVID-19 Assessment Centre opened Friday at Brewer Park Arena, there are now 10 confirmed cases of COVID-19.

"This number shows us that there are likely more travel-related cases that have gone on to cause local transmission of the virus in Ottawa," writes Dr. Vera Etches, chief medical officer, in a memo to the mayor and city council.

"Given the estimate that one case is likely to cause about two more and the doubling time is 4-5 days, there could now be hundreds to even a thousand cases in the community now," Dr. Etches warned, Sunday afternoon.

Dr. Etches asks everyone in Ottawa to limit non-essential trips out of the home and maintaining a distance of 1-2 meters from other people as much as possible.

Her recommendations also include keeping children home from daycare, if possible, and to check with their employers about options for working from home or implementing distancing at work.

Dr. Etches appears to know that some will perceive her warning as an over-reaction.

"Unless we act now to limit COVID-19 transmission in our community, we will not be able to keep the numbers who require hospital treatment all at once to a manageable number," Dr. Etches wrote.