We are currently in the middle of Operation Vaccinate Florida which runs from 2/10 to 3/10. At this point, local hospitals and health departments are screening and vaccinating nurses, doctors, and other health care workers who will be members of "Florida Response Teams" in each of the health districts of the state.

As one who is old enough to have been vaccinated twice, I am faced with the question of revaccination. My primary vaccination resulted in a transient blister and was felt not to represent a "take." I was revaccinated around age 9 with no reaction. At that time, no further vaccination was done for such "indeterminate" vaccinees. It was felt that "herd immunity" would protect those small numbers of persons with inadequte or no response to vaccine. With successful vaccination, duration of immunity is at least 10 years and may be 20 years among those re-vaccinated (N Engl J Med 346(17), April 25,2002). At the time, because vaccination was an ongoing program, the revaccination of adults was rarely done; protection of the older adults was dependent on the effect of "herd immunity."

We have heard of the dangers of vaccination. Current vaccine strains of Vaccinia virus result in serious complications in about 1:100,000 and death in about 1:1,000,000. If one was to vaccinate all 2.5 million health care workers who work in acute care hospitals, there would be, perhaps 7-8 deaths nationally. A strategy of vaccination followed by injection of Vaccinia immune globulin would be considerably more expensive (and there is yet limited supplies of VIG) but could reduce death rates down 10-fold or more.

Should we proceed onto stage 3 - vaccination of the general public? I think not. For an explanation of this opinion I encourage you to read this NEJM article A Different View of Smallpox and Vaccination byThomas Mack MD MPH.

Dr. Mack points out that smallpox is not as infectious as trumpeted in the lay press and in Bush Administration fear-mongering. Smallpox rates had already declined precipitously in most countries and the disease had been eliminated in many as a result of economic development long before the world-wide eradication program provided the coup de grace. Smallpox was absent in Europe (except Kosovo) for most of the 20th century even though universal vaccination was not practiced except in England. In the decades after WWII, most of the continental population was susceptible. In an analysis of the 945 cases in Europe which occurred after 1945 as a result of 51 episodes of introduction into the population, Dr. Mack reports:

Variola major was almost always transmitted at the bedside of the source, not at an external location. The source of infection was reported for about 96 percent of the cases that resulted from 51 introductions into highly susceptible European populations after World War II. Among the 18 cases, on average, per introduction, 3.8 occurred among household contacts and only 1.1 appeared among the multitude of community residents with no acknowledged exposure. None of the 945 cases involved disease contracted on an airplane, train, or bus. Any spread into the community from an introduction would thus be limited.
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Our greatest concern should be about transmission within hospitals. In postwar Europe, 4.4 cases per introduction occurred among caregivers and related professionals, and 6.7 cases occurred among hospital patients and visitors — numbers that together represent over 60 percent of the total. Only in hospitals has substantial transmission occurred at some distance from the beds of the source patients. Contact with infected linens has been responsible, as has, in one case, air recycled from a coughing patient to other rooms. Hospital spread also has been responsible for protracted outbreaks in Kuwait and Brazil, and it was responsible for the majority of cases in each of the last three outbreaks in the United States — in Seattle, New York City, and the Rio Grande valley.
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In the United States, secondary spread would probably be greatly limited by our high level of literacy, efficient means of personal and public communication, and organized public health services. Graphic photographs would saturate the media, and subsequent infectious patients would be recognized, avoided, and reported. Contacts would seek, not avoid, medical assistance and could be efficiently kept under surveillance wherever they were. Few new diagnoses would be expected more than a month or so after an introduction.

As Dr. Mack notes, actual past experience is likely to be a more accurate predictor of future events than models based on arbitrary assumptions. Certainly, each individual needs to make his own decision. For my $0.02, I would recommend vaccination of public health staff, nurses and doctors who would visit homes and enforce quarantines, ER employees and staff, and the staff of selected hospitals which can act as regional centers for referral of the suspected cases. Once cases are recognized, there is a 2-3 week incubation period during which contacts can be vaccinated, treated with variola immune globulin, or sequestered. This strategy draws a "ring" of vaccinated persons around each case and limits spread at minimal public risk and cost.