whistling will either keep you safe and give you the overall illusion of safety.
In other words, from my standpoint, I've put off the shingles vaccine for 8-10 years. No incidence in my ancestry of shingles but that's not a good excuse. In one way, the shingles vaccine is much more effective now than it was when my personal MD first recommended it, so waiting it out has given my an irrational cushion of thinking I've been smart to wait until the stuff actually works.