Need for developing a case definition and guidelines for immunization site pain as an adverse event following immunization [AEFI]:
Pain is defined as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” (International Association for the Study of Pain, IASP) . Pain is the most frequent local adverse event following immunization (AEFI) , , , . It results from the stimulation of nociceptive sensory neurons at the time of vaccine administration or inflammatory process in the damaged tissue afterward.
To date, there has not been a commonly accepted, standardized definition and related assessment of immunization site pain as an AEFI , , , , , , , , , . This hinders comparability and uniform reporting of pain across study settings or surveillance systems. Establishing criteria for assessing immunization site pain during and following immunization is important for individuals collecting, analyzing, presenting and/or communicating data on immunization pain as AEFIs.
A previous Brighton working group identified a list of local reactions from coding terminologies , ,  for injection site AEFIs that included a general term to describe “a local reaction” as well as more specific local reactions, including pain. Some definitions for local reactions have been defined and are published , , , , , . In this manuscript, we describe the case definition and guidelines for the assessment of pain as a specific local reaction. The case definitions for published local reactions can be accessed at the Brighton Website through a free online e-mail subscription process https://brightoncollaboration.org/public/resources.htm.
Sections 2 The case definition of “immunization site pain”, 3 Guidelines for data collection, analysis, and presentation 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 immunization site pain. Widespread use of this definition with its guidelines will improve data comparability and allow for a better understanding of immunization pain. The case definition and guidelines are intended to be applicable in diverse geographic, administrative, and cultural settings, regardless of differences in the availability of health care resources.
1.2. Methods for the development of the case definition and guidelines for immunization site pain as an AEFI
Following the process described previously , a Brighton Collaboration Local Reactions Working Group was formed in December 2008 with 19 inter-disciplinary members with public health, regulatory, clinical, academic, industry backgrounds, as well as expertise in pain. In January 2009, the working group began to develop the current definition of “immunization site pain” together with guidelines for data collection, analysis, and presentation of vaccine safety data.