B.3 Vaccine Safety

a) Objectives

Vaccine safety is an integral component of a national immunization strategy. Objectives of this component are to optimize the vaccine safety system, maintain professional and public confidence in the safety of vaccines, and address growing anti-immunization concerns by improving the following:

• The vaccine safety monitoring system (i.e., the passive surveillance system, the active surveillance system, and the ability to flag potential threats to safety).
• The public health response (i.e., the review and follow-up of potential vaccine-associated adverse events and the ability to mobilize capacity to respond to urgent situations).

b) Existing System

The current vaccine safety system in Canada can be described as follows:

(i)  Vaccine Safety Monitoring

• Passive Surveillance System: All professionals involved in the administration of vaccines are encouraged to report any potential vaccine-associated adverse events (VAAEs) to their local public health authorities, who report them to the provincial/territorial (P/T) level. P/Ts then report these events to Health Canada, which maintains a federal database of VAAEs. This passive surveillance system is nationwide, but reporting rates vary. The responsibility to report these events is legislated in some jurisdictions, but not in all. The format (i.e., paper versus electronic reporting) and timeliness of the reports to Health Canada from the individual jurisdictions vary, and jurisdictions have different activities and processes in place to verify that the suspected VAAEs meet the case definitions.
• Active Surveillance System: The Immunization Monitoring Program, Active (IMPACT), funded by Health Canada, and operated at 12 paediatric hospitals in Canada (representing most paediatric hospital admissions in Canada), conducts active surveillance for serious VAAEs through nurse monitors. IMPACT then reports the VAAEs to local health authorities, and assists in evaluating vaccine effectiveness.
• Signal Generation: "Signal generation" refers to the ability of the system to flag potential VAAE threats. Unusual or severe events are typically detected at the local level and reported to the P/T level, where an investigation may be initiated.Communications are also made with the federal level, and are usually by telephone.

(ii) Public Health Response

• Review/Follow-up of VAAEs: Health Canada's Advisory Committee on Causality Assessment (ACCA) is an expert advisory committee, with volunteer membership. It meets twice a year, with the mandate to select potential VAAE cases for review, to determine whether they were causally linked to the vaccine. Cases are selected from the federal VAAE database if they are severe or unusual, or they may generate research needs. Findings are communicated to P/Ts, and dissemination of feedback is left up to their discretion.
• Urgent Response or "Surge" Capacity: "Surge" capacity, which refers to capacity to respond to urgent situations or potential threats, is dependent on mobilizing human resources that are already functioning in positions with full-time commitments or other research priorities.

c) Gaps/Limitations of Existing System

The very success of immunization programs has proven to be one of their "weaknesses", as generations grow up in the absence of diseases that used to wreak havoc on the population and provided the stimulus for people to seek protection. There is a resulting low risk tolerance for vaccines, which has raised public expectations for vaccine safety, especially considering that vaccines are administered to healthy people. The presence of organized action groups opposed to immunization and capable of broad dissemination of information/opinions also highlights the need to address safety concerns in a more coordinated and effective manner.

The following are specific gaps/limitations of the current system, which need to be addressed to optimize the vaccine safety system in Canada:

(i)  Vaccine Safety Monitoring

• Passive Surveillance System
  • National data could be available in a more timely manner.
  • Standardization of data/reporting could be improved through the development of national guidelines for reporting and verification of VAAEs.
  • Identification of rare but serious potential VAAE threats could be improved, since (1) P/T databases may be too small for this, (2) denominator data on the number of vaccine doses administered may be difficult to access at a national level, and (3) more comprehensive analyses on the VAAE database could be conducted.
  • The capacity for data linkage with the existing federal VAAE database could be enhanced.
• Active Surveillance System: The primary focus of the active surveillance system has been on children, as opposed to adults.
• Signal Generation: Improvements in flagging potential VAAE threats could be made through better communication of information from the local level to the P/T level, to the national level, and through enhancements to the VAAE database.

(ii) Public Health Response

• Review/Follow-up of VAAEs:
  • Development of national guidelines on the management of VAAEs, and more extensive information sharing of existing P/T guidelines would improve the review/follow-up of VAAEs.
  • Advice/consultation on VAAEs could be provided to physicians and the public through a more organized network.
  • The ability to trace a problem "lot" (or batch) of vaccine could be improved.
• Urgent Response or "Surge" Capacity: There is a need for an enhanced surge capacity, as the ability of experts in the field to dedicate time to investigate/research an urgent issue would depend on their competing priorities/responsibilities.

d) Proposed Approach

The following changes could be made in order to address any limitations of the current system related to vaccine safety monitoring and public health response:

First, it is proposed that a network of dedicated F/P/T vaccine safety contacts be established in all jurisdictions. Such a network could improve signal generation and surge capacity. These individuals would be expected to identify and address potential vaccine safety issues, and would have a multi-purpose role of conducting surveillance, VAAE reporting, communication, signal generation, and environmental scanning. They could also be drawn upon in urgent situations requiring coordinated national action.

The second aspect of the proposed approach is to improve the current system of public health response. It is proposed that a clinical assessment/referral system be established to clinically assess and follow up individuals with suspected VAAEs. If physicians and other medical professionals require assistance in making the clinical assessment or determining the appropriate follow-up, they could contact the appropriate referral centre with expertise in this area for advice. One option under consideration is to expand the current role of IMPACT (i.e., which conducts active surveillance for serious VAAEs presenting at paediatric hospitals) to include an assessment and referral capacity.

The third aspect of the proposed approach is to have a vaccine safety committee to address any limitations of the current vaccine monitoring and public health response systems. The specific activities required by such a mechanism would be the following:

• Identification of potential issues
• Review of data/evidence
• Review of surveillance data and cases/clusters of concern
• Enhancing the ongoing vaccine safety monitoring through the passive system, including
  • Producing timely national surveillance reports on VAAEs
  • Developing national guidelines on reporting, verification, and management of VAAEs
  • Improving the current VAAE database (including data linkage capacity and provision of local access to data) and support registry network development
  • Exploring opportunities for enhancing ongoing vaccine safety monitoring through the active surveillance system (e.g., increased focus on the adult population)

Other important aspects of the Vaccine Safety component of the proposed NIS are research and communication. Research on vaccine safety issues is necessary to support evidence-based practice on VAAEs. Communication of safety data and monitoring activities are essential to maintaining professional and public confidence in vaccine safety, as well as to responding to potential VAAE threats. However, since research and communication are activities that cut across other components of the NIS, they will be discussed separately in section C of this paper.