Vaccine 25 (2007) 5735–5744 Progressive vaccinia as an adverse event following exposure to vaccinia virus: Case definition and guidelines of data collection, analysis, and presentation of immunization safety data  Patricia Nell a,1 , Katrin S. Kohl b,∗ , Philip L. Graham c , Philip S. LaRussa d , S. Michael Marcy e , Vincent A. Fulginiti f , Bryan Martin g , Ann McMahon h , Scott A. Norton i , Ingrid Trolin j The Brighton Collaboration Vaccinia Virus Vaccine Adverse Event Working Group for Progressive Vaccinia 2 a Airforce Reserve Command, United States Air Force, Sturgeon Bay, WI, USA b Immunization Safety Office, Office of the Chief Science Officer, Centers for Disease Control and Prevention, Atlanta, GA, USA c Department of Pediatrics, College of Physicians & Surgeons, Columbia University, Department of Epidemiology, NewYork Presbyterian Hospital, New York, NY, USA d Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, NY, USA e University of Southern California and University of California Los Angeles Schools of Medicine; Kaiser Foundation Hospital, Panorama City, CA, USA f Department of Pediatrics, University of Arizona Tucson, AZ and University of Colorado, Denver, CO, USA g Department of Allergy and Immunology, Walter Reed Army Hospital, Washington, DC, USA h Vaccine Safety Branch, Food and Drug Administration, Rockville, MD, USA i Walter Reed Army Medical Center, Washington, DC, USA j Medical Product Agency, Uppsala, Sweden Available online 4 May 2007 Keywords: Progressive vaccinia; Adverse event; Vaccinia virus; Smallpox vaccine; Immunization; Guidelines; Case definition 1. Preamble 1.1. Need for developing case definitions and guidelines for adverse events following exposure to vaccinia virus Following a declaration by The World Health Assem- bly in 1980 on the worldwide eradication of smallpox [1],  Disclaimer: The findings, opinions and assertions contained in this con- sensus document are those of the individual scientific professional members of the working group. They do not necessarily represent the official positions of each participant’s organization (e.g., government, university, or corpora- tion). Specifically, the findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention or the Food and Drug Administration. ∗ Corresponding author. Tel.: +1 404 639 8073. E-mail address: secretariat@brightoncollaboration.org (K.S. Kohl). 1 Retired., 2 Homepage of the Brighton Collaboration: http://www.brightoncollaboration.org. comprehensive smallpox vaccination programs around the world were stopped. Today, >50% of the world’s popu- lation is potentially unprotected against smallpox disease [2]. Recent warnings about the possible threat of using smallpox virus as a biologic weapon [3,4] prompted a resurgence of public health vaccination programs against smallpox. In this context, and in the broader context of a need for data comparability, as discussed in the overview paper in this volume, establishing criteria for assessing adverse events following smallpox (vaccinia) vaccination is impor- tant for clinicians administering the smallpox vaccine and appropriately treating patients with adverse events follow- ing immunization (AEFI), and also for scientists collecting, analyzing, and communicating data on AEFI. Understanding the normal changes and progression of a successful vaccine take is crucial for early recognition of complications. Frey et al. [5,6] completed two double-blind studies, using differ- 0264-410X/$ – see front matter. Published by Elsevier Ltd. doi:10.1016/j.vaccine.2007.02.088