Shingles ( The Varicella Zoster virus * A form of herpes not related to genital herpes* ) is treated with a vaccine called Zostavax. It is approved by the FDA for the use in adults over the age of 60 and in certain cases also between the ages of 50-59. It has not been widely studied for the use of adults younger than 50. This is why it is not used in adults younger than the age of 50 widely. It CAN be used if a doctor recommends it and individually prescribes it to their patient, but the risk of that falls back on that doctor... so it is rare they will prescribe it since there has not been enough studies on the effectiveness / risk ect. from the FDA. It is rare that someone will contract shingles before the age of 50 and if they do it is typically due to a compromised immune system due to something like an organ transplant, chemo, HIV ect ect. ( Hence why it is higher risk to elderly patients )
So yes, the vaccine CAN be given to people younger than 50, and the insurance company WILL cover it... but that's if the physician will write the script and wants to take the risk since so little information is known on the risk of administering the vaccine to the younger population at this time. :P