A North Korean defector was recently found with anthrax antibodies in his blood which has caused quite the stir, particularly among South Koreans and U.S. forces in South Korea.

There has been some confusion as to what this could mean. Why would someone have anthrax antibodies in his bloodstream? How is that indicative of some kind of weaponized anthrax? This article will discuss several of the more prominent possibilities.

But first: what are antibodies? Long story short, antibodies are small proteins that your body can make to neutralize diseases. You can develop antibodies through vaccinations or exposure to the biological agent (naturally occurring or weaponized) in question.

It’s important to realize that, with a thorough medical history and physical exam, health professionals would be able to determine the method of exposure to the defector. Here are four of the conclusions they may have come to:

Possibility 1: Modern anthrax vaccinations

Anthrax vaccinations take a strict regimen/series of shots into the muscle to work. It’s six doses at 0, 2, 4 weeks and 6, 12, 18 months consecutively, and missing a dose potentially makes the vaccine less effective. On top of this, once you’re done with the vaccine, you need boosters to keep it up. While there are newer systems emerging that allow for five shots instead of six, this is the type of system necessary to develop an effective vaccine to combat weaponized anthrax.

The task of getting immunizations out is usually passed down to medics or other on-site medical personnel. They have their list of names and they track down soldiers to make sure they have their latest shots. Soldiers certainly cannot be relied upon across the board to make all of these appointments themselves — while many would do it, many forget or don’t take it seriously. This is a problem in the U.S. military, and so it is possible that it would be a problem in the North Korean military as well.

All of this means that, in order to effectively vaccinate a military population against anthrax, you need to have some level of infrastructure to back that up. This while ignoring the difficulties in developing, manufacturing, storing/refrigerating and distributing the vaccines in the first place. Given North Korea’s limited resources, an effort like this would require a significant reason.