The Green Poison (also known as Dollar Flu) is a previously unknown strain of the smallpox virus with no functional vaccine or cure (known as Smallpox Variola Chimera). Compared to the original smallpox, not only does it incubate faster, it is also infectious during the incubation period, meaning it spreads and takes effect much more quickly. There are some people who are immune to catching this virus, but they are largely in the minority. The virus was created by Dr. Gordon Amherst as a means of population control, and was distributed via infected dollar bills during the Black Friday shopping insanity. Before people realized that it was smallpox, people took the epidemic for a particularly potent version of the annual flu season.

Dr. Kandel is a Virologist and is working on the cure. With the help of the Division agents, she manages to write various virus reports. After receiving viable samples of the original pathogen, she was able to conclude that it was indeed a manufactured weaponized disease. Studying the genome of the virus samples, she found traces from six separate pathogens: Dengue, Ebola, H1N1, Hantavirus, Marburg and Swineflu. (Note: Swine Flu is a strain of H1N1). Due to the rapid mutation of the virus, it is highly difficult for conventional drugs or antibody to identify and exterminate the virus as well as creating a proper vaccine to the disease.

When people die of this virus, it is known as "cashing out" due to it being spread by money.

Nicknames: Dollar Pox, Money Pox, Wages of Sin, Buck Flu, Dollar Bug, Cash Pox, Small Bill, and The Legal Tender.