Rash decisions: Why measles isn't a minor illness

baby with measles

It's one of the most infectious viruses on the planet spread by simply breathing the same air. It can linger in the air for up to two hours and may infect the central nervous system.

Measles was eradicated in Canada more than two decades ago but despite the availability of an effective vaccine, the highly contagious illness has made a comeback.

Dr. Kevin Katz
Dr. Kevin Katz, Medical Director of Infection Prevention and Control at North York General Hospital

“One of the first signs of measles is a high fever, which can be accompanied by a runny nose, cough, red watery eyes, and eventually a body rash,” says Dr. Kevin Katz, Medical Director of Infection Prevention and Control (IPAC) at North York General Hospital. “These symptoms might seem similar to the common cold, but measles has the ability to cause life-threatening complications.”

Serious complications include blindness, pneumonia and encephalitis (swelling of the brain). While rare, some people, primarily children, will develop subacute sclerosing panencephalitis (SSPE), a progressive neurological disorder causing seizures, coma, and eventually death.

“Measles is entirely preventable. Two doses of the measles vaccine (typically given in the combination MMR, or Measles, Mumps, Rubella vaccine) offers 97% protection, which is highly effective,” says Dr. Katz.

Herd immunity

While the measles vaccination coverage rate is about 89% nationwide according to the Public Health Agency of Canada, that's not high enough to offer herd immunity. Dr. Katz says herd immunity protects those who can't be vaccinated but in order to achieve that, closer to 95% of the population needs to be vaccinated for measles.

“Herd immunity is no longer effective if the immunization rate falls below 90%, which puts vulnerable populations at greater risk, including babies who are too young to be vaccinated.”

Measles cases up while vaccination rate down

Measles has become more prevalent around the world, including in the U.S. where the number of cases has surpassed a 25-year-old record. While the number of cases spike, the rate for vaccination has gone down. According to a UNICEF report, 287,000 Canadian children were not vaccinated for measles between 2010 and 2017.

As an infectious disease specialist, Dr. Katz has helped manage exposures to measles, which have proven to be complex.

“In an outbreak situation, it is difficult to identify how many people may have been exposed because they simply need to breathe the same air within an enclosed space like a library, shopping mall, school or emergency department,” says Dr. Katz. “Those who choose not to vaccinate are putting themselves and others, including loved ones, at risk. People who can't be immunized are virtually defenseless.”

More about measles

  • Measles symptoms typically appear within 10-12 days of exposure.

  • Nine out of ten people who are not immune to measles and are in close contact with an infected person will become infected.

  • The measles vaccine was first introduced in the 1960s and is safe and effective.

  • Children under the age of five are at greater risk for measles complications, including death.

  • The decline in measles vaccination rates is largely attributed to vaccine hesitancy and the anti-vaccination movement.

The number of measles cases around the world increased by 300% in the first three months of 2019 (World Health Organization).


Photo of baby with measles by Jim Goodson, M.P.H., Centers for Disease Control and Prevention

This article was first published in the June 2019 issue of The Pulse.

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