A substudy (CSP#403B) was initiated in November 2005 to offer investigational zoster vaccine to the placebo recipients of CSP#403. Vaccination was completed in March 2007 with 13,681 (75%) of the placebo recipients vaccinated. This substudy is closed. The safety results from the substudy were published in the Journal of Infectious Diseases (J Infect Dis. 2013 May 31 epub).