@cwal I've inquired about the Pall shower head. As you noted, it's expensive (for a shower head) and needs to be replaced every couple of months depending on use, making its cost-of-ownership non-trivial. In addition, there are a bunch of connections that need to be purchased and installed. I'm still figuring it out if it has a place in my shower. For now, I'm continuing with various precautions to avoid the pathogens we are prone to acquiring.