Re: synthétic DNA through vaccines
There are various synthetic DNAs for various purposes. There are even synthetic organisms that completely created in a laboratory. Although there are synthetic DNAs, they aren't different from a normal DNA.
It isn't necessary to use synthetic DNA to program you. Since DNA is in the cell, various drugs, environmental factors, neurochemicals, hormones etc. can program you and they can be placed in a vaccine to cause some programming in you.
If you mean changing the DNA of a person with an outside DNA source(synthetic or normal) through the vaccines, I would say it is possible. There is a field in genetics called Gene Therapy which cuts your defective gene and put a new, intact, functional gene in its place.
If you look at the technology that is currently available to normal scientists, gene therapy isn't an answer to the question you are asking because, as one of my professors who study gene therapy would like to say, there are three problems in gene therapy: Delivery, delivery, delivery. It is possible that people who work at top secret projects already get beyond those problems, and using vaccines to do such a thing.
For today, there are two classes of gene delivery method, one of them is viral gene delivery. I would imagine it is easy to take out the genetic material of a flu virus, place a programming DNA and label it as vaccine, but it may cause severe problems to the people who get the shots since scientists must calculate the docking site of the genetic material and its proliferation rate. If you want to kill everybody with vaccines, careless gene therapy is a perfect choice because you are basically creating a new virus! Have you watched "I am Legend" where they specifically talk about gene therapy and its outcomes?
The other is nonviral gene delivery, it has a few methods like liposomes etc but one of the methods is using nanoparticles to send DNA to a specific cell type so it is also easy for them to do such a thing in a vaccine.
In the end, it seems taking a vaccine can be more dangerous than we initially thought, if they want to do something bad to you. Considering H1N1 vaccines going around, I wonder what is in them...
edit: I think I didn't fully explain what is a synthetic DNA. It has the same building blocks of normal DNA, and Adenine Guanine, Cytosine, Thymine bases as usual, but its sequence is determined by the researcher. For example, they are used in the Polymerase Chain Reaction where you want to multiply a DNA segment, but you need a small complementary DNA fragment for DNA polymerase to hold onto your template and initiate chain reaction. For this reason you design a primer, 15-20 base pair and you send its sequence to companies. They create this synthetic DNA and send it to you for your use.