This study involves the use of investigational vaccines. A vaccine is a medicine that causes the body to make antibodies. Antibodies help destroy foreign substances that enter the body. The purpose of this study is to find the right dose of a new vaccine that is safe and produces a good immune response (how well your body recognizes and defends itself against harmful foreign substances). There are two Staphylococcus aureus toxoids (components or antigens) under investigation in this study; one of them is a protein known as rAT and the other is a protein known as rLukS-PV. They are being developed to see if they are effective at preventing infections caused by the bacteria Staphylococcus aureus.
Staphylococcus aureus is a leading cause of skin and soft tissue infections. Antibiotic resistance, such as seen with new community-acquired methicillin-resistant strains, presents a major challenge in treating and preventing these infections. Therefore, a preventative vaccine is considered a potentially better approach. This study assesses the safety and immunogenicity of monovalent and bivalent S. aureus vaccine components. Healthy adult subjects will be randomized to receive 1 dose of monovalent or bivalent toxoid vaccine, or placebo in a dose escalation schedule. Antigen-specific antibody will be measured by ELISA in sera collected for three months after injection. Safety data will be collected as 7 day reactogenicity diaries after each injection, adverse events and Staphylococcus aureus and skin and soft tissue infections will be collected through Day 84, and serious adverse events and chronic illnesses will be collected for the full 6 month study period. To evaluate the possible utility of booster doses, the cohort receiving the highest dose of bivalent antigen will have a 2nd dose administered at Day 84, with a new 7-day reactogenicity diary and sera collected after the 2nd dose. All subjects will be followed up with a 6 month phone call after vaccination or booster. The total subject observation period will be for 24 weeks from Day 0, plus 12 additional weeks for the cohorts that receive a 2nd dose. With a recruitment period of 4 months, the study duration is expected to be approximately 13 months.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
176
10, 25, 50 or 100 μg
10, 25, 50 or 100 μg
10, 25 or 50 μg
Placebo with adjuvant
Placebo saline
Brooke Army Medical Center
Fort Sam Houston, Texas, United States
Naval Medical Center Portsmouth
Portsmouth, Virginia, United States
Assessment of Safety Through Clinical Examinations, Clinical Laboratory Results, Self-reported Diary Reactogenicity Data and Adverse Event Reports
Adverse events, local reactogenicity, and systemic reactogenicity were assessed through clinical examination by study providers, clinical lab results, as well as review of subject-completed diary
Time frame: Up to 6 months
Immunogenicity: Geometric Mean Concentrations After First Injection, Completer Population
Immunogenicity is the ability of a particular substance, such as an antigen or epitope, to provoke an immune response in the body of a human or animal. Immunogenicity was determined on the basis of anti-rAT and anti-rLukS-PV IgG concentrations assessed by enzyme-linked immunosorbent assay (ELISA) in sera from blood samples collected on Days 0 (baseline), 14, 28 and 84 for those receiving a single dose of vaccine. For those receiving a second dose of vaccine, immunogenicity assessments were also conducted on Days 98 and 112. Immunogenicity was evaluated using the following metrics: geometric mean concentrations (GMCs), geometric mean fold increase (GMFIs) and seroresponse status. Seroresponse variables are normally defined in terms of exceeding a threshold.
Time frame: Up to 3 months
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