Vaccine safety and the IMPACT surveillance system
Canada has a unique program called IMPACT that complements existing national surveillance systems. IMPACT is a pediatric hospital-based national active surveillance network for adverse events in children following immunization and selected infectious diseases that are, or will be, vaccine-preventable.
Nurse monitors are at 12 children’s hospitals across Canada (including BC Children’s Hospital). They review all admissions to the hospital for certain serious illnesses. If a child with any of these illnesses had recently received a vaccine, a report is sent to the local health unit and to the Public Health Agency of Canada to be investigated further. These events are reported even if another cause may ultimately be found for the illness.
The active nature of the surveillance ensures a high level of vigilance for severe AEFIs in children.
Mandatory reporting by vaccine manufacturers
Vaccine manufacturers are required to report serious or unexpected adverse events to the Canada Vigilance Program, as mandated by the Food and Drugs Act and Regulations. The Canada Vigilance Program is Health Canada’s post-market surveillance program that monitors the safety profile of health products once marketed to ensure that the benefits of the products continue to outweigh the risks.
Vaccine Vigilance Working Group (VVWG)
The VVWG was created in 2004 as part of the National Immunization Strategy to strengthen vaccine safety in Canada. It includes representatives from all federal and provincial/territorial immunization programs, as well as Health Canada regulators and IMPACT.
The group’s activities include providing a national vaccine safety sentinel network to rapidly share and disseminate information regarding vaccine safety issues or signals to appropriate stakeholders.
It’s often difficult to determine if an adverse event was caused by the vaccine or something else that happened around the same time the vaccine was given — for example, an infection or onset of a chronic condition that would have occurred even if the person had not been immunized. As a result, the details of all AEFI reports are carefully reviewed. Rates of adverse events in immunized people are compared to those of the same in people who are not immunized. This can help determine if the vaccine has a true safety concern. Some types of events are further investigated to clarify the cause. For instance, people with allergic reactions may be tested to find out which vaccine component caused the reaction.