Vaccine Safety

Canadian Adverse Events Following Immunization Surveillance System (CAEFISS)

Announcement: May 2005: New Name for Canada's vaccine safety surveillance system The Vaccine Associated Adverse Events Surveillance System (VAAESS) has had its name changed to Canadian Adverse Events Following Immunization Surveillance System (CAEFISS). This new name is in harmony with international standards and emphasizes that reported events follow immunization but are not necessarily associated with vaccine.

Adverse reactions to vaccines are monitored by the Vaccine Safety Unit (VSU) of the Centre for Immunization and Respiratory Infectious Diseases.

CAEFISS - voluntary surveillance system

The Canadian Adverse Events Following Immunization Surveillance System (CAEFISS) was developed to provide a national monitoring system for reporting adverse events and suspected adverse events following immunization. The objectives of the system are to:

1. ensure continued safety of marketed vaccines in Canada;
2. monitor adverse effects that may be caused by a vaccine;
3. identify any unusually high rates of adverse events, both with individual vaccines and individual lots of vaccine;
4. provide timely information that can be made available to potential recipients as well as health care providers so that they can weigh the risks and benefits of immunization, and
5. identify areas that require further epidemiologic investigation and research or problems that require immediate investigation.

CAEFISS is a voluntary reporting system (with the exception of four provinces, Ontario, Saskatchewan, Nova Scotia and Quebec, that have mandatory reporting requirements) in which health care providers (mainly public health nurses and physicians) report to local, provincial and/or territorial public health authorities events they feel are temporally associated with an immunization. These authorities, as well as vaccine manufacturers and occasionally other agencies that receive information, forward all such reports for aggregation on a national level to the VSU. Particular adverse events of public health interest are included on the national version of a reporting form that is used (with modifications) by all provinces and territories.

Other severe or unusual events are also solicited and reported if the health care provider feels it may have been due to the administration of a vaccine. The Canadian Immunization Guide, 7th Edition 2006, provides information to health care providers on the nature of adverse events occurring with specific immunizing agents.

The reports are entered into an electronic database. To calculate adverse event rates, the VSU obtains lot specific data from vaccine manufacturers on the number of doses of their products distributed across the country. These "vaccine distribution" data are used as an approximation of the actual number of doses of vaccine administered. However, because of varying reporting practices, and the fact that the exact number of adverse events following immunization is unknown, differences in adverse event rates require cautious interpretation. Although these denominator data are limited in reliability, they are very useful in generating signals that should be investigated. Further estimates of denominator data are obtained from vaccine coverage studies.

IMPACT - active surveillance system

In addition to the voluntary reporting system (CAEFISS), Canada also has an active surveillance system for serious adverse events following immunization, vaccination failures and selected infectious diseases. This system is known as IMPACT (Immunization Monitoring Program ACTive) and was established in 1990 to further support the timely reporting of adverse events, particularly for the most serious reactions in children.

IMPACT is operated through a contract with the Canadian Paediatric Society and involves a network of 12 paediatric centres across Canada which comprise over 2,000 paediatric beds with over 75,000 children admitted annually. This represents over 90% of all paediatric tertiary care admissions in the country. At each centre a nurse monitor and clinical investigator perform active case-finding based on a regular review of admission records. They are assisted by a network which includes admitting department staff, infection control nurses, neurology ward staff and physicians, infectious diseases staff, and medical records technicians. IMPACT continues to reassure the public that vaccines are safe and that the benefits of vaccination for parents and children far outweigh the potential risks of serious reactions.

Advisory Committee on Causality Assessment (ACCA)

In 1994, a multidisciplinary group called the Advisory Committee on Causality Assessment (ACCA) was established to review all case reports meeting criteria for severity or "unexpectedness". This group is composed of specialists in pediatrics, public health, epidemiology, infectious diseases, immunology, neurology and adverse event surveillance. The committee meets for two days, once or twice a year and conducts monthly telephone conferences to review selected cases and discuss vaccine safety issues. Should an emergent concern require intervention, further teleconferences are arranged. Cases that are reviewed are stripped of all identifiers and distributed to each member in advance. Selection criteria for case review include, for example, all cases of meningitis/encephalitis, encephalopathy, febrile seizures, deaths and other events of a serious nature that have led to hospitalization. Each case is reviewed using the WHO-UMC (World Health Organization-Uppsala Monitoring Centre) causality assessment criteria of Very Likely, Probable, Possible, Unlikely, Unrelated, or Unclassifiable to determine whether the adverse event was related to the administration of the vaccine(s).

International Surveillance

The Public Health Agency of Canada is also a contributor to the World Health Organization's International Drug Monitoring Program and is a reference centre of that program for vaccines. The WHO program aggregates case reports from over 75 countries and is uniquely placed to analyze world-wide adverse reaction data. Collaboration is also very active on a technical level with many national and international agencies, in particular the Canadian Paediatric Society and public health authorities in the provinces and territories.

Guidelines to Clinicians for Reporting Adverse Events

For the reasons stated above, timely and complete reporting of vaccine associated adverse events is crucial. All health care providers, whether they immunize or not, should be alert to the potential range of adverse events and their temporal relationship to vaccines. History taking should therefore elicit any recent vaccination received.

The Adverse Event Following Immunization Report Form is used nationally, although the provinces and territories may have different versions, or may use this form with their own logo and address. In the passive system, health care providers (mainly public health nurses and physicians) report to local, provincial and/or territorial public health authorities adverse events that follow immunization or may have been due to the administration of a vaccine. These authorities, as well as vaccine manufacturers, forward all such reports, to the Public Health Agency of Canada. All reports received from both active and passive surveillance systems are aggregated and stored in a computerized, web-enabled Adverse Event Following Immunization (AEFI) database at the Agency.