Larry Jaques fired this volley in news: snipped-for-privacy@4ax.com:
I took one four or five week regimen of it almost 30 years ago, and although my sensitivity slowly increases with time (not being exposed very often) that was enough.
It's a progressive-dose thing... 1/4 tab a day for a period, then half, up to two tabs a day... then done for decades of immunity.
LLoyd