The most effective antigen for such a vaccine would be whole cells. Bacterial cell walls are highly antigenic, because they are unique. Nothing in the human body is similar.

But bacteria evolved a tendency to develop strain variations in their cell walls in order to evade the immune system. To take advantage of that, biowarfare researchers produce unusual strains to foil immunization attempts.

Since cell wall strains for weaponized anthrax are expected to be varied and unknown, the vaccine researchers in the US decided to use a genetically engineered toxin protein instead of the cell wall for the vaccine antigen.

One problem with that approach is that a protein is not as visible as early as the cell wall. The toxin is not produced until the bacterial cell has been moved around in the body. The immune system needs to recognize the cell wall at the start of the infection.

Another problem is that proteins are not good antigens for vaccines. They are too much like the body's own proteins. This means the vaccine does not easily produce good immunity, and there is a tendency for cross-over, which could result in auto-immune problems.

A protein is the only possible product of genetic engineering. For this reason, genetically engineered vaccines do not have good characteristics.

Since no countries but Russia and the US can do significant research on Anthrax, and Russia is not the problem, there is not a good logic to vaccinate for anthrax.

Iraq has no ability to create a sophisticated Anthrax weapon. This demonstrates how important it is to properly evaluate the nature of the problem.