Cellulitis at injection site

Need for developing case definitions and guidelines for cellulitis at injection site as an adverse events following immunization
Cellulitis is an inflammatory condition of the skin [1], and is a rare adverse event following immunization. Although cellulitis resulting from chemical trauma to the skin can occur, most cellulitis after immunization is the result of bacterial infection by indigenous flora colonizing the skin and appendages, or by a wide variety of exogenous bacteria [2], [3], [4]. Because cellulitis after immunization can occur due to unsafe injection techniques or vaccine vial handling or storage, and because it can clinically be confused with other skin reactions to immunization, it is important to develop standardized diagnostic criteria to guide the appropriate public health intervention, and to improve global comparability of vaccine safety data on cellulitis.

Sections 2 Case definition for cellulitis at injection site, 3 Guidelines for data collection, analysis, and presentation of cellulitis at injection site of this paper provide the case definition and guidelines for data collection, analysis, and presentation that the Brighton Collaboration Local Reactions Working Group has developed for the standardized collection and assessment of information about cellulitis at injection site. Widespread use of this definition with its guidelines will improve data comparability and allow better understanding of the adverse event. The case definition and guidelines are intended to be applicable in diverse geographic, administrative, and cultural regions, regardless of differences in the availability of health care resources.

1.2. Methods for the development of the case definition and guidelines for cellulitis at injection site as an adverse events following immunization
Following the process described in the overview paper [5], a Brighton Collaboration Local Reactions Working Group was formed in December 2001 with 12 members with public health, regulatory, clinical and academic, and industry backgrounds. The Working Group identified 16 injection site reactions to be defined based on their frequency or severity. It has previously published its case definition with guidelines for nodule at injection site [6]. The Working Group, whose composition is slightly different for each of the definitions depending on availability and interest in a particular topic by working group members, has since developed four additional case definitions with guidelines published in this volume. The member composition and results of the web-based surveys completed by the reference group and subsequent discussions in the working group can be viewed at: http://brightoncollaboration.org/internet/en/index/working_groups.html.

To guide the decision-making for the case definition and guidelines, a literature search identified English and non-English citations of local reactions. The search was expanded to gather reports specifically of cellulitis related to vaccines or immunization (MEDLINE 1976–001; MeSH search terms “cellulitis” and “bacterial-vaccines” or “viral-vaccines” or “immunization” or “vaccination”). The literature search also included a review of medical dictionaries and general medical, pediatric and infectious diseases textbooks related to the diagnosis and assessment of cellulitis at injection site as an adverse event following immunization (AEFI). A systematic review of the incidence and clinical symptoms of cellulitis following immunization was not found in the literature reviewed that included 120 articles of local reactions in general and 15 additional articles on cellulitis. None of the references reviewed from the search were informative in regard to definitions but described case scenarios where cellulitis had occurred after immunization.

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