 This study is a single-center, randomized, double-blinded, placebo-controlled, Phase 1, dose de-escalation study to evaluate the safety, reactogenicity, and immunogenicity of a purified inactivated, alum-adjuvanted ZIKV vaccine ZPIV administered in a homologous prime-boost regimen to healthy male and non-pregnant female adult subjects living in a flavivirus-endemic area. This study will enroll 90 healthy male and non-pregnant female subjects between the ages of 21 and 49 and will be conducted at Ponce Medical School Foundation, Inc.-CAIMED in Ponce, Puerto Rico. The entire duration of each subjects participation is approximately 26 months including recruitment and collection of data on the safety and reactogenicity of the study vaccine and collection of samples for the assessment of immunogenicity. This study is expected to take approximately 42 months to complete. Two dose levels will be evaluated. Each subject will receive either placebo or 5 mcg Group 1 or 2.5 mcg Group 2 of 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 homologous boost on Day 29, and a follow-up period of 24 months post boost vaccination. The study will begin with enrollment of 2 sentinel subjects in Group 1 who will receive 5 mcg ZPIV open label. One sentinel subject will be vaccinated, followed for one day for safety and reactogenicity, and if no halting rules are met per determination of the PI and co-PI, then the second sentinel subject will receive 5 mcg ZPIV open-label. Both sentinels will be followed for safety through Day 8 and if no predefined halting rules are met and no safety concerns are identified, then enrollment of the remaining 43 Group 1 subjects will proceed in double-blind fashion. The same procedure will be used for administration of the boost vaccination to the Group 1 sentinels: 1 sentinel can be either will receive 5 mcg ZPIV open-label, be followed for one day for safety and reactogenicity, and if no halting rules are met, then the 2nd sentinel will receive the boost vaccine. Both sentinels will be followed until Day 8 after 2nd vaccination for safety and reactogenicity and if no halting rules are met, then boost vaccination of the remaining 43 Group 1 subjects can proceed. Enrollment of the 2.5 mcg ZPIV group Group 2 can begin after all subjects in Group 1 have received the 1st dose of vaccine and been followed until Day 8 for safety and reactogenicity, provided no halting rules are met or safety concerns identified. As this is a dose de-escalation study, no sentinel subjects will be used in Group 2. All 45 subjects in Group 2 will receive study product or placebo in double-blind fashion. In total, 40 subjects will receive 5 mcg ZPIV, 40 will receive 2.5 mcg ZPIV, and 10 will receive placebo saline. All subjects will receive a homologous boost of ZPIV or placebo 28 days post-prime if no halting rules precluding second vaccination are met. Solicited local and systemic reactogenicity data will be collected from all subjects through Day 8 after each vaccination. Unsolicited adverse events will be collected from all subjects through Day 57 28 days after 2nd vaccination. SAEs, AESIs, and history of new medical conditions with onset after the first vaccination will be collected for the duration of the study. Blood for evaluation of antibodies to ZIKV by ELISA and neutralizing antibody assays will be collected at Visit 00, prior to each vaccination, and at multiple timepoints afterward. Primary objectives are: 1 Assess the safety and reactogenicity of a homologous prime boost regimen of ZPIV given at two different dose levels in a dose de-escalation format in healthy adult subjects who live in Puerto Rico, a flavivirus endemic area. 2 Compare the safety and reactogenicity profile of ZPIV after each vaccination, between dosage groups, and by pre-vaccination flavivirus immune status. Secondary Objectives are: 1 Assess the humoral immune response to a homologous prime-boost regimen of ZPIV after each dose of vaccine as determined by kinetics of the immune responses, seroconversion rates, and Geometric Mean Titers GMT overall, and compare results between dosage groups and by pre-vaccination flavivirus immune status. 2 Assess the durability of the humoral immune response to ZPIV at 6, 12, 18, and 24 months after the second vaccine administration overall, and compare results between dosage groups and by pre-vaccination flavivirus immune status. 