Safety and immunogenicity of three different formulations of an adjuvanted varicella-zoster virus subunit candidate vaccine in older adults: A phase II, randomized, controlled study

• We investigated a herpes zoster vaccine candidate at different antigen doses, and with or without the AS01B Adjuvant System.
• All adjuvanted vaccine formulations were immunogenic and well-tolerated in adults ≥60 years of age.
• Two vaccinations with the adjuvanted vaccine candidate induced a greater immune response than one.
• The dose of varicella-zoster virus glycoprotein E impacted humoral but not cellular immune responses.

BackgroundThis study investigated the safety and immunogenicity of different formulations and schedules of a candidate subunit herpes zoster vaccine containing varicella-zoster virus glycoprotein E (gE) with or without the adjuvant system AS01B.MethodsIn this phase II, single-blind, randomized, controlled study, adults aged ≥60 years (N = 714) received one dose of 100 μg gE/AS01B, two doses, two months apart, of 25, 50, or 100 μg gE/AS01B, or two doses of unadjuvanted 100 μg gE/saline. Frequencies of CD4+ T cells expressing ≥2 activation markers following induction with gE were measured by intracellular cytokine staining and serum anti-gE antibody concentrations by ELISA.ResultsFrequencies of gE-specific CD4+ T cells were >3-fold higher after two doses of all gE/AS01B formulations than after one dose of 100 μg gE/AS01B or two doses of 100 μg gE/saline. Frequencies were comparable after two doses of 25, 50, or 100 μg gE/AS01B. Serum anti-gE antibody concentrations were comparable after two doses of 50 or 100 μg gE/AS01B and higher than in the other groups. Immune responses persisted for at least 36 months. Reactogenicities of all gE/AS01B formulations were similar but greater than with gE/saline.ConclusionsThe three formulations of gE/AS01B were immunogenic and well tolerated in adults aged ≥60 years. Two vaccinations with gE/AS01B induced higher immune responses than one and the dose of gE impacted humoral but not cellular immune responses (NCT00434577).