In the only case on record where smallpox broke out in an place where part of the population had been vaccinated long before, it proved to be the case that some immunity was retained by most of the people who had been vaccinated even decades before. As a group, they were less likely to be infected, and if infected less likely to die, than the entire population in the exposure area.
It was also the case that those vaccinated before, considered as a group, had more deaths, and more serious illness from smallpox than they had had as a group from the vaccination. The numbers are somewhat better now, for complications, and deaths expected from vaccination, and the statistical expectations from smallpox itself are highly speculative, but somewhat better than they were half a century ago.
From a military preparedness point of view, if the entire population, gets vaccinated, someone has spent millions of dollars for a weapon system that now represents a bigger threat to the country that possesses it that it does to the country it was intended to attack.
Three to five hundred deaths out of the 2,391,399 people who died in 1999, is a very small fraction. It is less than three and a half percent of the number who died from AIDS that year. It is even less than the number who died of malnutrition, in the same year. If this number represents a number that indicates that we should be changing our medical policies, then perhaps we should consider the policies that allowed more than that number of people to starve to death during one year.
This will not be a repeating statistic. It will be a single incidence, and it will then be followed by a very small number of subsequent deaths as the policy includes new, and unvaccinated individuals.
Still, I agree with prevailing opinion, that the vaccination of large numbers of people should be controlled and planned to maximize the effectiveness of the immunity created. First responders, hospital workers, and those likely to be exposed to the first responders and health workers. Until the likelihood of an attack is seen to be much more probable, it seems prudent to prepare, and plan for universal vaccination, but not to initiate such a program, pending a change in status quo.
Tris