This always blows my mind. We are currently breathing in the DNA of the trees, animals, and people around us—and we’re leaving ours behind for them, too. We’re all one big genetic soup.
The immune system destroy all the DNA in unexpected places in case it's a https://en.wikipedia.org/wiki/Viroid or something. Better safe than sorry.
One of the important steps in mRNA vaccines was to surround the mRNA with a lipid to ensure it can survive long enough to enter a cell. Naked mRNA would not have worked.
> This always blows my mind. We are currently breathing in the DNA of the trees,
At this time of year, believe me, I am aware of the inhaled tree DNA setting off my pollen allergies.
"Soup" is a good word. Pieces of DNA resulting from destruction by nucleases and other enzymes.