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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.
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