Fergy, depending when you got your first vaccination, your immunity may have worn off. The vaccine is only good for 10 years, 15 max. If you are close to this number, consider your immunity gone. Other factors to consider, your overall general health and phyisical condition. In your line of work,I would assume that your are healthy and in good shape. Your past medical history also plays a factor. If you have ever had liver problems (hepatitis) or chronic lung problems(severe asthma, severe bronchitis, emphysema) The answer is no, don't take it. If you have an immune system problem or are on immuno-suppressive therapy ( aids, lupus or having chemo for cancer) you are not elligable for the vaccine. In these cases, it WILL kill you. Most people will suffer mild side effects. They are: swelling, redness, tenderness, hot feeling at the injection site. Fever, sweating, general flu-like symptoms for 24 to 36 hours after the shot. There can also be a rather large scar left afterward (about the size of a quarter).
About 2% to 4% of people will experience medium to severe symptoms. These are like the mild ones only stronger. Those with severe symptoms are usually hospitalized, due to the fever and dehydration that occurs.
Ok, after all that, here is something else to think about. If you become infected with smallpox, there is no drug or therapy to cure you. It must run it's course. The side effects of the diesease can be treated, (Itching, fever, dehydration) but the disease can not. In 85% (approx) of the cases it is fatal.
I 'm sorry but I can't say wheather or not you should take it. All I can do is give you some information. I will say that in my personal case, I am not able to take it as I am on immuno- therapy.
Considering your line of work and the proximity to DC, I would think seriously about this. Whatever you decide, remember to be careful out there and thanks for keeping a part of the country safe for the rest of us. If you need more infor please don'r hesitate to let me know. I know this is long, but I hope it helped.