Thanks to routine immunization, many diseases that were once widespread in Canada are now preventable. While these diseases are now far less common, and their once life-altering impacts are rarer, declining vaccination rates can still lead to outbreaks.
This National Immunization Awareness Week, Immunize Canada is encouraging Canadians to get immunized, protect their future, and not let history repeat itself. It’s more important than ever to remember how these vaccines changed history, and why immunization matters.
Here’s a look at how routine immunization has changed the course of polio, measles, and whooping cough in Canada.
Polio
Poliomyelitis (polio) is an infectious disease caused by the poliovirus. It is most common in children under 5 years. Though it begins as an infection of the gut, it can progress and invade the nervous system. These cases can progress to paralysis.
Polio first caused outbreaks in Canada in the 1910s. By the 1920s, larger outbreaks began to occur in one province after another. By 1953, according to the Canadian Encyclopedia, 9,000 polio cases and 494 deaths had been reported in Canada. In 1955, a vaccine developed in Canada significantly reduced cases of polio. It was eventually replaced by a new vaccine across the country in 1995/1996.
After decades of routine childhood immunization, the World Health Organization declared polio eradicated in Canada in 1994 – but polio is still present in other countries and could be brought back by travelers. Routine immunization remains an important to ensuring the disease won’t return in Canada.
Measles
Measles is one of the most contagious infections. Of the people who aren’t immune to measles, 90% will become sick if they encounter the virus. Measles can lead to serious health complications and, in some cases, may be fatal. (Source: Government of Canada)
Before vaccines were available for measles, 10,000 – 90,000 cases were reported in Canada each year. Measles vaccine was introduced in 1963. From 1969 – 1983, an average of only 9,863 cases were reported annually. By 1998, measles was considered eliminated in Canada.
Outbreaks of measles have recently been reported in some provinces in Canada, including Quebec and Ontario.
When rare outbreaks of measles take place in Canada, vaccines reduce the number of people who will get sick. A single dose of the current measles vaccine is around 85% to 95% effective at preventing infection. Two doses are closer to 100% effective.
In order to keep measles from reaching the people in our communities who aren’t vaccinated (herd immunity), we would need about 95% of people to be fully vaccinated. Measles can still spread quickly, particularly in areas with low vaccination rates.
Whooping cough
Pertussis, also known as whooping cough, is a contagious disease caused by a bacteria. In adults the disease is relatively mild. Symptoms can be more serious in infants due to their narrow airway passages.
Vaccines for pertussis have been in use for decades. These immunizations have greatly reduced the spread of the disease and protected many people from severe illness and death.
The Government of Canada reports that from 1935 until 1945 (two years after the first pertussis vaccine was introduced in Canada), there were over 15,000 annual cases of pertussis in Canada. As immunization became more widespread, cases declined. By 1965, 20 years after the vaccine was first introduced, there were less than 5000 cases per year.
Pertussis is still endemic (regularly found) today. It is easily transmitted and infants who are too young to be protected by a full vaccine series are especially vulnerable.
Read more about whooping cough vaccines in Canada.
Vaccines Still Matter
When case numbers of diseases like polio, measles, and whooping cough increase, it puts vulnerable populations at risk. This includes infants, seniors, pregnant people, and those with weakened immune systems. Staying up to date on vaccinations protects both individuals and communities – and is crucial to ensuring we don’t let these vaccine-preventable diseases make a permanent comeback.
Check current vaccine recommendations and schedules on the Government of Canada website here to find our which vaccines you may be missing.
Further Reading
Canada and the Development of the Polio Vaccine (The Canadian Encylopedia)
Measles (Immunize Canada)
Measles Vaccine: Canada Immunization Guide (Government of Canada)
Pertussis (Whooping Cough) Vaccines: Canada Immunization Guide (Government of Canada)
Poliomyelitis (polio) vaccines: Canadian Immunization Guide (Government of Canada)
The problem with pertussis, and how a human challenge trial could help (Canadian Center for Vaccinology – challengeunit.ca)
Vaccines work: Case counts of 6 vaccine-preventable diseases before and after routine vaccination (Government of Canada)