Bioterrorism agents are classified according to priority.

The Certification Study Guide (6th edition) explains that bioterrorism agents are categorized by the Centers for Disease Control and Prevention (CDC) into Categories A, B, and C based on their potential impact on public health. Category A agents represent the highest priority because they pose a severe threat to national security and public health. These agents are characterized by ease of dissemination or transmission, high mortality rates, potential for major public health impact, and the ability to cause public panic and social disruption.

Smallpox (variola virus) is a classic and well-recognized Category A bioterrorism agent. The study guide emphasizes that although naturally occurring smallpox has been eradicated globally, the virus remains a major concern because the general population lacks immunity, person-to-person transmission is efficient, and outbreaks would require extensive public health response. Smallpox also necessitates strict isolation precautions and rapid vaccination strategies during suspected or confirmed cases.

The other options fall into lower categories. Q fever and brucellosis are classified as Category B agents, as they are moderately easy to disseminate but typically cause lower mortality rates. Influenza, while capable of causing pandemics, is not classified as a bioterrorism Category A agent.

Understanding bioterrorism classifications is essential for infection preventionists, particularly in emergency preparedness, surveillance, and response planning—key knowledge areas emphasized on the CIC exam.