KEYWORDS:
vaccine safety; adverse events; immunization; case definitions

BACKGROUND:
Progress in research and surveillance of immunization safety has been hindered by a lack of globally accepted and implemented standardized case definitions of Adverse Events Following Immunization (AEFI). This is because "safety" in the realm of immunizations can only be inferred indirectly by the relative absence of multiple AEFI.

OBJECTIVE(S):
The Brighton Collaboration was formed as an international collaboration to enable comparability of immunization safety data from clinical trials and postmarketing surveillance through the development of standardized case definitions for AEFI.

METHOD(S):
Working groups of up to 20 volunteers have been formed for the first six AEFI definitions. Volunteers come from various medical disciplines, vaccine safety, public health, pharmaceutical and regulatory agencies, and have experience in the developed and developing world. Under coordination of The Brighton Collaboration, working groups arrive at case definitions through literature review and consensus process. Initial case definitions will be finalized after a comment period from groups representative of immunization safety, and will be globally disseminated via the web and other means.

RESULT(S):
Information about the collaboration and calls for volunteers have been widely disseminated. Since the first six working groups have been formed, draft definitions for the first set of AEFI (i.e., fever, local (injection site) reactions, intussusception, prolonged crying, cerebral convulsion and hypotonic-hyporesponsive episode) have been developed. We built the methodological framework for a format of case definitions with applicability in settings with various levels of resources and in different geographic regions.

CONCLUSIONS(S):
We have established the structure and process necessary to develop widely acceptable standardized case definitions for AEFI. Ongoing commitment and a growing circle of volunteers will be essential for the success of the collaboration.

LEARNING OBJECTIVES:
1) Understand need for standardized vaccine safety case definitions
2) Understand methodological issues of standardized case definitions
3) Describe items included in the developed definitions