Patients with previous shingles were excluded from the Shingles Prevention Study that evaluated the zoster vaccine, and as a result potential benefit isn't well known. Waning immunity to varicella-zoster virus is the primary risk for development of shingles. But, when it occurs, the immune system is then boosted. Given that patients who have had shingles show natural boosting of VZV immunity, one would expect that immunizing these patients would be of limited benefit. However, after an episode of shingles immunity will again wane over time with eventual increased risk for recurrence. It hasn't been well defined as to what optimal long-term booster dosing schedule is needed for prevention of shingles. In my opinion, it’s reasonable to offer zoster immunization to those individuals who are otherwise indicated for vaccine and have had a previous episode of shingles, particularly if this episode was many years (i.e. 10-20) earlier.