Though this makes the same, it improves the readability of the code.
Have fun, Alexei
The suggestion to move the Epilog/Prolog to the first plot is helpful. Still, after all this discussion, I am inclined to say that comparison with the simplicity of mpl's axvline suggests that there is a missing feature in Mathematica: perhaps, a keyword for Rectangle coordinates to get the full graph extent. In economics and finance graphs, this is a very common need.