Ontario's Chief Medical Officer of Health says vaccine hesitancy is the major factor for the current outbreak of the measles virus.
Measles is spreading primarily in unimmunized communities across southwestern Ontario.
Dr. Kieran Moore said the health unit wants to see children protected.
"The vast majority of children that we're having to see hospitalized to date have been in unimmunized children, 95 per cent, and so that is our target population," he said.
According to Moore, two doses of the measles vaccine can give 97 per cent protection against the virus.
He said the vaccine has been used for decades.
"This virus is a relatively constant virus and the vaccine is well matched to it, so two doses is our means of giving life-long protection," Moore said.
Health units are working to promote confidence in the vaccine by highlighting its benefits and providing information and resources.
Moore said this takes time and effort.
"They've been doing that for years in trying to build the relationships that are essential to decrease the hesitancy and build the confidence that's necessary," he said.
Since the onset of the measles outbreak, more people have been checking into the health units to make sure they are fully immunized.
Moore said vaccines help mitigate the spread and outside of unimmunized areas there are high rates of immunization.
"The wall of community immunity through immunization in Ontario is very strong and this, I believe will only continue to spread in unvaccinated areas of our community," he said.
Since the outbreak, health units have had to establish rapid testing, doctors and nurses have been educated on symptoms and hospitals have been protected against transmission.
Moore said ahead of this outbreak the measles virus has been under control since 1998.
Across Ontario there have been 1,243 confirmed cases, in comparison to 60 to 70 in past years.
The health units with the highest number of cases are the Southwestern Public Health, Grand Erie Public Health, Huron-Perth Public Health, Chatham-Kent Public Health and Windsor-Essex Public Health.
"There is no question in having enough vaccines, we have it and it's available and is accessible through primary care and through our health unit," said Moore.
He reminds those who are up to date on the measles vaccine that the risk of getting it is rare.
It is expected there will an increase in cases in May and June but it's hoped there will be a decrease in the summer months.
Symptoms of the measles include a fever, red eyes, cough, sneeze, small white spots in the mouth and a red blotchy rash.
The virus can live in air for up to two hours when someone infected breathes, coughs and sneezes.
Anyone who thinks they have the virus and are unvaccinated, pregnant or have a weakened immune system are advised to call their local health unit.