Measles outbreaks and high numbers of children sickened with whooping cough and chicken pox have Canadian public health officials and pediatricians concerned about the consequences of parents’ vaccine hesitancy.

"We are concerned about hesitancy around vaccines and particularly people not getting their children immunized on time," Ontario’s Chief Medical Officer of Health Dr. Arlene King told CBC Radio’s Metro Morning today.

"Many of these diseases are really invisible to us, although they're only a plane ride away," and a risk for those at any age who are unvaccinated.

King said she often works in Africa, where the serious consequences of many vaccine preventable diseases are front and centre. That’s often not the case both for Canadian parents and health-care providers who continually need to be educated about what the diseases look like so they’re able to diagnose patients.

On Wednesday, Ontario announced that starting in September families will need to prove children have been immunized against whooping cough, meningococcal disease and chickenpox for children born in 2010 or later.

Currently, King said children can be suspended from school during outbreaks of six vaccine preventable illnesses if they don’t have proof of immunization. The vaccines are publicly funded.

King said there is a lot of unfounded, unsubstantiated information and myths out there, which is why she recommends that people speak to their health-care provider.

Fewer than than two per cent of parents request a statement of exemption, King said.

While most children are immunized on time, as many as 20 per cent of parents remain hesitant, meaning they have concerns about immunization, delay immunizations or outright refuse recommended vaccines, according to the Canadian Paediatric Society.

New Brunswick and Manitoba also require public school students to show their immunization records to attend school.

Dr. Frank Atherton, Nova Scotia's deputy chief medical officer of health, said they need better information about where there are pockets of under-immunized individuals.

Nova Scotia is creating a vaccine registry. No national registry exists.