Smallpox vaccinations are often fatal for the immune-impaired, especially those with AIDS/HIV. Immune-impairment is usually caused by medical treatment, commonly for heart ailments and cancer, diseases like hepatitis, and intravenous drug use. AIDS/HIV victims are only a small fraction of the millions of immune-impaired Americans. Many people with functioning immune systems but other conditions, both normal (pregnant ladies, babies under a year old, etc.) and abnormal (some skin disorders, especially eczema), are more susceptible to vaccination-caused complications which sometimes afflict even the healthiest. These groups should not be vaccinated.
The major problem is that people vaccinated against smallpox are briefly dangerous to these groups. Smallpox vaccine uses a "live" virus related to smallpox, called vaccinia, which produces a small oozing sore on the inoculation site 2-3 days later which quickly scabs over, plus flu-like symptoms. About a third have the oozing sore and flu symptoms for longer periods - sometimes several weeks. Contact with pus from the sores (even dried pus floating off and inhaled) can cause a fatal or crippling vaccinia infection in the immune-impaired or complication-susceptible, though that is far less likely to happen than through vaccination.
Experts therefore additionally recommend against smallpox vaccinations of any persons living with the immune-impaired and complication-susceptible. This totals about 25 percent of all Americans.
The usual way to protect people from such secondary infections is to have those recently innoculated whose vaccination sores are still oozing wear a bandage - something like the big knee/ankle bandaid you can find in drugstores - until the sore scabs over. Back when vaccinations were mandatory this was a tiny proportion of the population on any given day, and those were almost entirely young children who stayed at home anyway.
But if millions of adults are voluntarily vaccinated, hundreds of thousands of them will be out on the streets posing threats to the immune-impaired and complication-susceptible. Thousands of them might die, and several times that number could be crippled.
This is not an easy decision.
Anyway, couldn't you isolate those who have just been immunized for a couple of days (that needn't mean keeping them in hospitals, you could order them to drive home and stay home for a couple of days)? Alternatively, couldn't you immunize everybody else within a short period of a week or so, and isolate the immunodeficient during that period?
Especially if any danger that vaccinating others might present to the immunodeficient is minimized in one of these ways, shouldn't we bear in mind that the immunodeficient would be those in the greatest danger if a smallpox epidemic ever got started?
I've often wondered why the vaccine seemed less potent over the years. My grandmother had a scar the size of a silver dollar, ca. 1890; my mother had a scar the size of a quarter, ca. 1913; I have a scar the size of a dime, ca. 1940; and my oldest daughter, ca. 1960; had a dreadful reaction to the vaccine, but bears no scar. My younger children did not react at all.
The daughter who suffered the dreadful reaction also had such a bad case of chickenpox that her pediatrician sais she'd seen noting like it since treating smallpox in India (1967). The other children in the family were barely sick with the chickenpox.
The unfortunate truth, however, is that this "lifetime immunity" has probably worn off because they stopped giving the shots.