Biotech Station (Science Career Reward) has two main interactions: "Make Medicine" and "Make Virus".
If you make medicine, you can sell it, or a sim who is sick can perform the "Take Medicine" interaction and drink it, which lowers the severity of their disease, pretty much guaranteeing recovery.
If you make virus, then you can dispose of it, or a sim whose current mood is -50 (half red) or worse can perform the "Take Virus" interaction and drink it, which makes the sim sick with the Mysterious Disease.
What I didn't like was that the game checked the sim's mood bar to determine whether they should be able to take the virus. In the Sims 2, the mood bar does not indicate depression, sadness or happiness. It is just an averaged value of the sim's needs. The aspiration bar, on the other hand, does indicate how happy a sim is. So, obviously the game should check the sim's aspiration score. This is exactly what this mod does. Now, if your sim's aspiration score is within the bottom bar, they can take the virus.
In order to unrar this mod, you need the latest version of 7zip
This mod modifies one resource in the objects.package file. Any other mod that modifies this resource will conflict with this mod:
Interaction - Take Medicine/Virus - TEST/Group:0x7F37F90B/Instance:0x00001015