Trial Evaluating the Immunogenicity and Safety of an Adjuvanted Epstein-Barr Virus (EBV) Glycoprotein 350 Vaccine in EBV-seronegative Persons

Study Description: This is a multisite randomized, double-blinded phase 1/2 study to evaluate the immunogenicity and safety of a 3-dose regimen of an adjuvanted EBV glycoprotein (gp) 350-Ferritin nanoparticle vaccine in EBV-seronegative persons. We hypothesize that the vaccine will be safe and induce a potent EBV gp350-specific immune response. Sixty EBV-seronegative participants will be randomized; 30 will receive the EBV gp350-Ferritin vaccine and 30 will receive the placebo at Days 0, 30, and between 60 and 90. Participants will be followed for 1 year after the third dose with an option to follow for a second year. Primary Objective: To evaluate the safety and immunogenicity of an adjuvanted EBV gp350-Ferritin vaccine administered to healthy EBV-seronegative adults. Secondary Objectives: 1. To evaluate the safety of the adjuvanted EBV gp350-Ferritin vaccine administered to EBV-seronegative adults up to 30 days after the third dose of study vaccine. 2. To preliminarily evaluate the efficacy of the adjuvanted EBV gp350-Ferritin vaccine administered to EBV-seronegative adults. Exploratory Objectives: 1. To compare safety and immunogenicity of an accelerated 3-dose vaccination schedule (Days 0, 30, and 60 to 90) with the traditional vaccination schedule evaluated in NCT04645147. 2. To further evaluate the immunogenicity of the EBV gp350-Ferritin vaccine. Primary Endpoint: Change in mean EBV neutralizing antibody from Day 0 to 30 days after the third dose of study vaccine in EBV gp350-Ferritin vaccine recipients as compared with placebo. Secondary Endpoints: 1. Safety through 30 days after the third dose of the study vaccine: 1. Solicited local and systemic reactions within 7 days after study vaccine administration. 2. Unsolicited adverse events (AEs) through 30 days after the third dose of the study vaccine. 3. Serious adverse events (SAEs) through 30 days after the third dose of the study vaccine. 2. Reduction of viremia measured by quantitative polymerase chain reaction (qPCR) in EBV gp350-Ferritin vaccine recipients as compared with placebo in participants who become infected with EBV. 3. Reduction of EBV infection as measured by new anti-EBV viral capsid antigen (VCA)-specific immunoglobulin (Ig) G or IgM or new EBV viremia for up to 2 years post-vaccination as compared with placebo. 4. Reduction of EBV-related infectious mononucleosis as defined by signs and symptoms consistent with infectious mononucleosis with laboratory evidence for new EBV infection for up to 2 years post-vaccination as compared with placebo. 5. Time to EBV infection as measured by new anti EBV VCA IgG or IgM or new EBV viremia. 6. Time to infectious mononucleosis as defined by signs and symptoms consistent with infectious mononucleosis with laboratory evidence for new EBV infection. Exploratory Endpoints: 1. Change in mean EBV neutralizing antibody from Day 0 to 30 days after the third dose of vaccine in EBV-seronegative vaccine recipients in the standard dosing regimen (Days 0, 30, and 180) vs accelerated (Days 0, 30, and 60 to 90). 2. Safety through 30 days after the third dose of study vaccine in the standard dosing regimen (Days 0, 30, and 180) vs accelerated (Days 0, 30, and 60 to 90). * Solicited local and systemic reactions within 7 days after vaccination. * Unsolicited AEs through 30 days after the third dose of study vaccine. * SAEs through 30 days after the third dose of study vaccine. 3. Increase in EBV gp350 IgG antibody in blood and/or EBV gp350 IgA antibody in saliva in vaccine recipients as compared with placebo. 4. Increase in CD4+ T-cell response in study vaccine recipients from baseline (pre-vaccine) to 30 days after the third dose of vaccine as compared with placebo in participants who become infected with EBV.