Public health officials said those born before 1970 are considered immune, either from having it or being exposed to the highly contagious virus. They recommend anyone born after 1970 to be vaccinated against measles twice. If there’s doubt about your immunization history, get a shot.
A single dose is considered to have a 95 per cent effectiveness rate, which rises to 99 per cent with the two recommended.
When the Public Health Agency of Canada validated its national immunization coverage survey against local immunization records in 2011, it found 95.2 per cent had received at least one dose of measles-containing vaccine by two years of age and 94.9 per cent had received at least two doses by seven years of age.
Public health officials in Toronto are currently investigating how four people were infected with measles without any known connections between them.
In the U.S., there have been 102 cases of measles so far this year in 14 states, Dr. Anne Schuchat, director of the National Center for Immunization & Respiratory Disease at the U.S. Centers for Disease Control and Prevention, said Tuesday. There are about 20 million measles cases around the world each year.
In Canada, a "reasonably high percentage of the population" is vaccinated, said Prof. Linda Levesque, who studies vaccine safety at Queen's University in Kingston, Ont.
Slow pace of science
The minority includes both those philosophically opposed to vaccines and those who forgot to get a second dose.
"When the good science comes, and in some cases with the MMR vaccine and autism it was a decade later that the good science debunked the link between the two, by then I think it's too late," she said. "I think we need to adopt a much more pro-active approach."
Levesque would like to see parents reminded of how the risk of measles infection, albeit rare, are more frequent than possible side-effects of the vaccine itself.
Common symptoms of measles infection include fever and rash. About one in three of those who contract the infection will have one or more complications including diarrhea, ear infections (which can lead to permanent hearing loss), pneumonia, encephalitis (inflammation of the brain) or seizure.
Less than one in a million people who receive the vaccine will experience a severe reaction, according to the American Academy of Pediatrics.
Provinces are rolling out reminder systems for vaccinations in general, such as a portable electronic record and text message reminders sent to people when they're due for another dose.