This also means that individuals need to be immunized annually for reliable protection. Despite these problems, the influenza vaccine works, and works well. 5 Serious side effects are very rare. There is compelling evidence that immunization against influenza of groups at high risk of complications is cost-effective. This debate is, however, based on small and specialized studies that are not remotely comparable to the size of the proposed Ontario program.
Pandemic influenza is the most serious predictable public health emergency.
Pandemics are caused by a major change, or antigenic shift , in the influenza virus. A new pandemic strain has the capacity to spread worldwide in a matter of months. Unchecked, we could expect it to infect millions of Canadians, cause hundreds of thousands of admissions to hospital and tens of thousands of deaths. Immunization is the only effective means currently at our disposal of combating an influenza pandemic. The last pandemic was more than 30 years ago.