I had Lyme a few years ago and for the past year or so I've been taking 5000 IUs of Vitamin D3 on days when I won't be out in the sun. I feel great and haven't gotten sick in over a year when everyone around me is hacking and wheezing from whatever goes around.
I agree that antibiotics are totally over-used but I don't agree with Marshall or Proal when it comes to vitamin D and sunlight being bad for us, we are designed to be outside and get lots of sunlight.