Centers for Disease Control and Prevention
CDC Home Search Health Topics A-Z
peer-reviewed.gif (582 bytes)
eid_header.gif (2942 bytes)
second_navbar.gif (585 bytes)
 
Research

Modeling Potential Responses to Smallpox as a Bioterrorist Weapon

Martin I. Meltzer,* Inger Damon,* James W. LeDuc,* and J. Donald Millar†
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; and †Don Millar & Associates, Inc., Atlanta, Georgia, USA

Figure 6. Daily and total cases of smallpox after a combined quarantine (25% daily removal rate) and vaccination campaign for two vaccine-induced reductions in transmission and three postrelease start dates. The graphs show that, when combined with a daily quarantine rate of 25%, vaccination must achieve a >33% reduction in transmission to stop the outbreak. At a 25% daily removal rate of infectious persons by quarantine, a cohort of all those entering their first day of overt symptoms (i.e., rash) is entirely removed within 17 days (18 to 20 days after incubation) after the first day of overt symptoms, with 90% removed within 9 days. Removal is assumed to start same day as vaccinations. The daily rate of removal by quarantine relates only to the removal of those who are infectious (i.e., are overtly symptomatic). The rate does not include any persons who may be quarantined along with overtly symptomatic patients, such as unvaccinated household contacts. Vaccinating contacts or potential contacts is assumed to result in 25% and 33% reductions in transmission, so that the transmission rate is reduced from 3 to 2.25 and 2 persons infected per infectious person, respectively. Data were generated by assuming 100 initially infected persons and an initial transmission rate of 3 persons infected per infectious person. For clarity, the graphs of daily cases do not include the assumed 100 initially infected persons. The graphs of total cases include those initially infected.

Back to article
Figure 6. Daily and total cases of smallpox after a combined quarantine (25% daily removal rate) and vaccination campaign for two vaccine-induced reductions in transmission and three postrelease start dates. The graphs show that, when combined with a daily quarantine rate of 25%, vaccination must achieve a >33% reduction in transmission to stop the outbreak. At a 25% daily removal rate of infectious persons by quarantine, a cohort of all those entering their first day of overt symptoms (i.e., rash) is entirely removed within 17 days (18 to 20 days after incubation) after the first day of overt symptoms, with 90% removed within 9 days. Removal is assumed to start same day as vaccinations. The daily rate of removal by quarantine relates only to the removal of those who are infectious (i.e., are overtly symptomatic). The rate does not include any persons who may be quarantined along with overtly symptomatic patients, such as unvaccinated household contacts. Vaccinating contacts or potential contacts is assumed to result in 25% and 33% reductions in transmission, so that the transmission rate is reduced from 3 to 2.25 and 2 persons infected per infectious person, respectively. Data were generated by assuming 100 initially infected persons and an initial transmission rate of 3 persons infected per infectious person. For clarity, the graphs of daily cases do not include the assumed 100 initially infected persons. The graphs of total cases include those initially infected.
 


Home | Top of Page | Current Issue | Expedited | Upcoming Issue | Past Issue | EID Search | Contact Us | Accessibility | Privacy Policy Notice | CDC Home | Search | Health Topics A-Z

This page last reviewed December 08, 2001

Emerging Infectious Diseases Journal
National Center for Infectious Diseases
Centers for Disease Control and Prevention