Emergency response to a smallpox attack: the case for mass vaccination

Area of Science:

• Epidemiology
• Public Health Preparedness
• Infectious Disease Modeling

Background:

• Bioterrorist attacks with smallpox pose a significant public health threat.
• Current interim response policies involve case isolation, contact tracing, and selective vaccination.
• The effectiveness of these policies compared to immediate mass vaccination is not well-established.

Purpose of the Study:

• To model the impact of smallpox bioterrorist attacks in large U.S. urban areas.
• To compare the effectiveness of the interim traced vaccination policy against immediate mass vaccination.
• To estimate the number of smallpox cases and deaths under different vaccination strategies.

Main Methods:

• Development and implementation of a smallpox disease transmission model.
• Simulation of a bioterrorist smallpox attack scenario in a large U.S. city.
• Comparison of outcomes between an interim traced vaccination policy and immediate mass vaccination.

Main Results:

• Mass vaccination, initiated immediately upon attack recognition, resulted in significantly fewer smallpox cases and deaths.
• Mass vaccination led to much faster eradication of the epidemic compared to the traced vaccination policy.
• These findings held true across a wide range of disease and intervention parameters.

Conclusions:

• Immediate mass vaccination is a more effective strategy than the interim traced vaccination policy for controlling smallpox bioterrorism.
• The existing policy of initiating traced vaccination and only switching to mass vaccination if necessary is outperformed by immediate mass vaccination.
• Enhanced preparedness strategies should prioritize rapid, widespread vaccination in response to a smallpox attack.