Month 1 - phone call and collection of adverse events (AEs) and concomitant medications 6 week visit - post dose lab collection: Interferon-G Enzyme-Linked Immunospot Assay (ELISPOT) and GPELISA, VZV Glycoprotein Enzyme-Linked Immunosorbent Assay (also known as Varicella Zoster antibody titre) Months 2, 3 and 4 - phone call and collection of AEs and concomitant medications