Risks and Benefits of Preexposure and Postexposure Smallpox Vaccination

• Main Author: Martin I. Meltzer
• Format: Article
• Language: English
• Published: Centers for Disease Control and Prevention 2003-11-01
• Series: Emerging Infectious Diseases
• Subjects: United States
• Online Access: https://wwwnc.cdc.gov/eid/article/9/11/03-0369_article
• ISSN: 1080-6040; 1080-6059

This article presents a model and decision criteria for evaluating a person’s risk of pre- or postexposure smallpox vaccination in light of serious vaccine-related adverse events (death, postvaccine encephalitis and progressive vaccinia). Even at a 1-in-10 risk of 1,000 initial smallpox cases, a person in a population of 280 million has a greater risk for serious vaccine-related adverse events than a risk for smallpox. For a healthcare worker to accept preexposure vaccination, the risk for contact with an infectious smallpox case-patient must be >1 in 100, and the probability of 1,000 initial cases must be >1 in 1,000. A member of an investigation team would accept preexposure vaccination if his or her anticipated risk of contact is 1 in 2.5 and the risk of attack is assumed to be >1 in 16,000. The only circumstances in which postexposure vaccination would not be accepted are the following: if vaccine efficacy were <1%, the risk of transmission were <1%, and (simultaneously) the risk for serious vaccine-related adverse events were >1 in 5,000.