The voluntary take up rate would have to be very high to give any useful "herd immunity". We have a problem in Britain at the moment with the take up of the MMR vaccine. The optimum vaccine take up rate is 97% or above, but in some areas it is below 80%. This has caused some isolated outbreaks of measles in these low take up areas. To prevent an uncontrollable Smallpox epidemic we would need over 80% of the population to be vaccinated. Its very unlikely that this could be done quickly by a voluntary vaccination campaign.
A key question is whether or not people who want voluntary vaccination will have to pay for the vaccine? Is there enough vaccine available to do volunary vaccinations and still vaccinate people in communities that are exposed after an attack? If there isn't enough vaccine and people have to use privately sourced vaccines for voluntary vaccination, then some impoverished groups will be left unprotected.
I often hear ignorant people in Britain say that children are the most at risk from a Smallpox attack. I don't know when routine Smallpox vaccination ended in the USA, but in Britain it ended in the 1960s. Therefore, people in their mid-30s are fully susceptible to it. Apparently, the Russians continued routine vaccination into the late 1970s. They weaponised Smallpox of course, so they had to make sure their population was immune.
Its funny the number of people who have told me that they are confident that they are safe even though they were vaccinated back in the 60s. I have a Russian colleague who was vaccinated in 1974 and she told me she wasn't worried about a Smallpox attack. I informed her that the Smallpox vaccine is only guaranteed to prevent infection for 5 years and 10 at the outside, although the disease suffered is usually less severe if Smallpox is contracted within 20 years. Oh well, whatever gives people hope!
If Al Qaeda has Smallpox, they are most likely to have the extremely deadly India-1967 strain of Smallpox, which the Soviets apparently gave to North Korea and goodness knows who else. Apparently, they manufactured 20 tons of it for use in their ICBMs and other weapons systems. Thus it certainly would be the most likely strain to have been stolen and sold to the highest bidder. This strain has caused Smallpox in people who were vaccinated more than 10 years before exposure, although the mortality rate is much lower than for non-vaccinees. The mortality rate with this strain is at least 50% for non-vaccinees and not the usual 30%, which is seen with most other strains.
Your observation regarding "herd immunity" is interesting. Calculation of herd immunity is related to the virulence and the vectors of infection. In a bioterror attack, the strain you describe would be most concerning. Yet, I am still left questioning the conclusion of ACIP.
Instead of permitting dilution of existing vaccine and instead of permitting families to voluntarily pay for the vaccine privately, the ACIP chooses to withhold the vaccine.
This is most peculiar given the responsibility of the federal gov't to "Provide for Common Defense". Clearly, this vaccine falls into the realm of "common defense".
Your comments appear to support release of the vaccine more than withholding. Am I correct in conclusion?