As I understand it, the information on anthrax and Hep B was taken strictly from a titer. In other words, if i were tested for antibodies, I would test positive for Hep B due to vaccinations. I would guess that was the case with the soldier.
The U.S. has stopped giving military personnel the anthrax vaccine, but when I did a clinic at the arsenal in 2003, I had to pick up the vaccine from another floor and take it to the lab where I was working. I then watched them give the vaccine to a soldier about to be deployed to the middle east who had somehow missed an earlier vaccination. He looked in pain.