Between 2000 and 2013, there have been 20 confirmed cases of measles in the Calgary area. Of those, only two cases were confirmed where the person had been immunized, said MacDonald.
Symptoms appear to be milder in those who've been immunized, said MacDonald.
The latest case involves a student around the kindergarten or Grade 1 age from Clear Water Academy, said MacDonald.
Staff and students at the university prep school that have not been immunized will be send home for a couple weeks.
The other cases include a 16-year-old student and a 16-month-old infant, both of whom contracted the virus in the Philippines, said MacDonald. The baby is the one who had not been immunized.
The fourth person with the virus is a 36-year-old, according to MacDonald.
The vaccination has at least a 95 per cent effectiveness rate, said University of Calgary microbiologist Glenn Armstrong, who is an expert in infectious diseases.
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