The whole monastery has been offered a Hepetitus-B vaccine (nuns and yogis included). I recently had my second dose. According to wikipedia, after the third dose, I won't need any booster and I will protected for life. I could have gotten this when I worked at Bayer on the Advia blood meter, but it seemed like it would take too long and it was said at that time to only last a few years. The 3 dose schedule is only 6 months.