No, but the feasibility of engineering viruses (which is simple in the movies) is unclear. I myself doubt that viruses can be made more virulent without damaging them in other ways.
>>Also, we do not have to be innoculated UNLESS there is absolute certainty that we are being exposed....correct?????<<
The State cannot require you to be immunized, but they can quarantine you against your will if you refuse.
I don't think vaccine refusal is going to be much of an issue after an attack...
I imagine genetic engineering is like any other form of engineering: the engineer must make a series of choices, and each choice limits his future options. For example, ebola is a very lethal virus. It is, however, extremely fragile--exposing it to five seconds of direct sunlight (or an artificial equivalent) is sufficient to kill it.