Ottawa Public Health is criticizing a local daycare that says it offers a “vaccine-free environment,” calling the approach a public health risk.

The owners of the unlicensed daycare in the suburb of Orleans say their facility is for parents like them who are worried about vaccines and choosing not to vaccinate their kids.

The daycare owners are no longer doing interviews, but have told several local media outlets that they believe recently-vaccinated children carry around live viruses that can then infect others.

Dr. Carolyn Pim, an associate medical officer of health with Ottawa Public Health, says the daycare owners are misinformed.

Pim says some of the vaccines that are given to children, such as the measles, mumps, and rubella (MMR) vaccine and the varicella (chickenpox) vaccine do contain live but weakened viruses.

The virus amount is large enough to cause a child's immune system to begin creating antibodies to the virus, but small enough that it won't actually cause illness.

She says the virus is safe in those with normal immune systems and those who have had the vaccine will not spread the virus to others.

"There isn't any evidence that there is transmission of disease from one person to another. The vaccines are safe and they really are the best way to protect kids," Pim told CTV's Canada AM in Ottawa.

Pim says her greatest concern with the vaccine-free daycare is that if a vaccine-preventable illness is introduced into the daycare, it will spread like wildfire.

"As we know, daycares are a really great breeding ground for infectious diseases. And if I were a bacterium or a virus, I'd have thought I had won the lottery if I found a daycare where there were kids who weren't immunized," she said.

Pim says last year, Ottawa saw four measles cases. This year so far, there have been none.

The Ottawa daycare is making headlines at the same time as the city of Toronto is dealing with a outbreak of measles.

At least six people have become infected and there could be more cases to come, since public health officials are unsure how the six acquired their infections.

None of the six had contact with one another and none had travelled to the U.S. where an outbreak tied to Disneyland has caused at least 121 infections.

Toronto health officials have discovered that one of the infected adults recently visited a daycare in the city's west end. A makeshift clinic has now been set up at the West End YMCA, and Toronto Public Health is warning parents that children who attended the West End YMCA daycare may be at risk of contracting the virus.

The parents of those children are being urged to speed up the vaccination process to prevent infection or to lessen the severity of the illness if they have already contracted the virus.

It can take up to 10 days after infection with measles for symptoms to appear.