RISKS OF VACCINATION AND A SMALLPOX EPIDEMIC: STELLA MODELS SUITABLE FOR INSTRUCTION OF FIRST RESPONDERS

摘要

A Stella model of a smallpox epidemic was created using the classic SIR model. An instructional interface was designed for nursing students but is easily adapted for instruction of other groups of first responders. Probabilities of risk were based on values from historical smallpox epidemics when possible. Effects of significant numbers of people who have compromised immune systems were considered, although historical information was not available since HIV, organ transplantation and modern chemotherapy techniques were not prevalent before the eradication of smallpox. The high mortality rate of smallpox (variola major) makes the importance of herd immunity and of effective isolation procedures especially clear. About half of the smallpox transmission during outbreaks in developed countries occurred in medical facilities. Medical personnel need to be trained as primary defenders of our homeland security in the case of a bioterrorism event. There are also clear benefits to improving public health preparedness even if no bioterrorists ever attack. Effective isolation of infected people and rapid immunization of people who are likely to be exposed are standard techniques for the containment of any epidemic. A second model addresses risks of vaccination and problems with using a live vaccine on people who have severely compromised immune systems. Reintroducing the smallpox vaccine could cause significant mortality among the general population unless there is careful screening of vaccinees.