This Phase 1 study is a single-center, double-blinded, placebo-controlled, to evaluate the safety, reactogenicity, and immunogenicity of ZPIV administered in a homologous prime-boost regimen to Flavivirus-naïve healthy male and non-pregnant female adult subjects.

Three dose levels may be evaluated: 5.0 mcg, 2.5 mcg, and 10mcg of ZPIV. Each subject will receive either a placebo or ZPIV administered by intramuscular (IM) injection on Days 1 and 29. The study will consist of a screening period of up to 28 days, a vaccination period in which subjects will receive a prime dose of vaccine on Day 1 followed by a boost on Day 29, and a follow-up period of 12 months post boost vaccination.

The entire duration of each subject's participation is approximately 14 months including recruitment and collection of data on the safety and reactogenicity of the study vaccine and samples for the assessment of immunogenicity. This study is expected to take approximately 30 months to complete from initiation through the availability of a final report on the primary outcomes of safety and the secondary outcomes of humoral immunity to ZIKV.

The primary objectives of this study are to 1. Assess the safety and reactogenicity of a homologous prime-boost regimen of ZPIV given at three different dose levels, and 2. Compare the safety and reactogenicity profile of ZPIV after each vaccination and between dosage groups.

The secondary objectives of this study are to 1. Assess the humoral immune response overall and by dosage group to a homologous prime-boost regimen of ZPIV as determined by kinetics of the immune responses, seroconversion rates, and peak Geometric Mean Titer (GMT) and to 2. Assess the durability of the humoral immune response overall and by dosage group to ZPIV at 6 and 12 months after the second vaccine administration.