IFNG and herpes zoster: Considering the importance of the CMI response for herpes zoster vaccine development, we used ELISPOT to measure levels of interferon-gamma (IFN-γ) (Figure 4F) and interleukin-2 (IL-2) (Figure 4G) after the booster, comparing only the FR-gE/XUA01, 2000 PFU, Shingrix, and saline groups based on the preceding outcomes of IgG1/IgG2a ratios (Figure 4D).