Zostavax is now FDA approved for 50 year olds and up-04/22/2011

The FDA has approved Zostavax for patients 50 and older (http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm248390.htm). 
Prior to this the vaccine was available for  patients 60 and older. 
Read the following link which summarizes the  study that helped in this decision:   http://www.internalmedicinenews.com/index.php?id=495&cHash=071010&tx_ttnews[tt_news]=53263