Do vaccines really work? Over the past decade, some parents in the U.S., Canada and Europe have started refusing to give their kids the recommended childhood vaccinations. They worry about safety, believing vaccines may cause autism or other disorders. Denial that the vaccines have any benefit at all has been a part of this particular type of refusal. (Parents in other parts of the world oppose vaccines for other reasons.)
Although no vaccines are 100 percent effective, they can have a big impact on the health of a population. Toronto's public health department put together this visual of the rates at which Canadians got different infections before and after the advent of some common childhood vaccines.
You can learn more about studies of vaccine safety and efficacy with Popular Science's new guide.