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You are right that the CDC are deluding themselves if they think they can successfully stop a Smallpox outbreak begun by determined terrorists using the 'ring vaccination' protocol, without hundreds or perhaps thousands of deaths. That method may have worked in the campaign to eliminate Smallpox, but it would be very inefficient against a simultaneous outbreak occurring in dozens of areas all over the country. The terrorists would probably use a covert release method, such as spreading freeze-dried Smallpox particles at a railway, airport or bus station. Before the primary victims start showing serious symptoms the virus would be in 40 or more towns and cities around the country and probably also abroad. This conclusion is supported by a study which was actually done by the US military on this dispersal method in a bus station using spores from a harmless Bacillus species.

The idea that epidemiologists could trace everyone who might have been infected and vaccinate their communities in time to stop a disaster is wishful thinking. The only way to prevent a successful Smallpox attack would be mass vaccination in advance. Unfortunately, if al Qaeda don't have Smallpox then we would look rather silly using mass vaccination, since we would loose about 180 people according to the accepted Smallpox vaccination risk assessments. The only problem is, are there enough doses of Smallpox vaccine to do 97% of the US population? If there aren't then it would be better to keep them for 'ring vaccination', instead of just giving them to people who want them.

Dear David,

Thanks for the thoughtfulness of your response. The scenario you have described is the worst case scenario. I'm sure that the intelligence authorities have to be working to identify such plans. If the terrorist organizations are willing to create a plan like 9-11, and since there are operatives still out in the field; the shipping of the weapons becomes the issue.

Currently, the anthrax attack in Sept 01 has escaped identification. It appears to me that the perp had sufficient containment to limit spread in an apartment or business. Somewhere there has to be traces of the same germ from the packaging. If the traces do not exist, then the packaging occured elsewhere and (more importantly) the manufacturing of the weapons occured outside the United States.

This poses the possibility that we have already been subjected to a biological attack by a foreign nation. I submit this is a higher possibility than domestic terrorism. The only gov't with enough to pull off the scheme is Iraq. North Korea probably doesn't have anthrax molecular biologists available. But, middle eastern college students abound in our nation. If one was bought off and entered Iraq, then they may be the perp.

Regarding ring vaccination strategies and the epidemiology of the spread of smallpox, there is one issue that you have omitted from your scenario. There is the possibility with voluntary immunization of the populace of creating "herd immunity". When a herd of cattle are susceptible to a disease, then it spreads faster if all cattle are susceptible. However, once a certain percentage of people are immune, it is possible to contain the spread of the disease more easily. Because not every individual is susceptible, some of the contagion decreases in the total population.

I submit to my colleagues on this board (who are physicians and public health officers) that herd immunity is the issue in our national defense against bioterrorism. Certainly, polio is not a likely weapon of choice. Nearly every American is immune to the virus. However, it was our own decision to stop protecting our children and it was our own lack of foresight that has created the first new generation totally susceptible to smallpox in over 100 years!

God help the politician who is silent when we request formally for the stockpiles to be released.