xml: <clinical_study>
    <!-- This xml conforms to an XML Schema at:
      https://clinicaltrials.gov/ct2/html/images/info/public.xsd -->
    <required_header>
      <download_date>ClinicalTrials.gov processed this data on September 20, 2023</download_date>
      <link_text>Link to the current ClinicalTrials.gov record.</link_text>
      <url>https://clinicaltrials.gov/ct2/show/NCT06007183</url>
    </required_header>
    <id_info>
      <org_study_id>EBSI-CV-317-008</org_study_id>
      <nct_id>NCT06007183</nct_id>
    </id_info>
    <brief_title>Long-term Follow-up Study to Evaluate Safety and Immunogenicity of PXVX0317 Single or Booster Vaccination</brief_title>
    <official_title>A Long-term Follow-up Study to Evaluate Safety and Immunogenicity of a Chikungunya Virus Virus-like Particle Vaccine (PXVX0317) in Healthy Adults and Adolescents After Either a Single or Booster Vaccination Dosing Regimen</official_title>
    <sponsors>
      <lead_sponsor>
        <agency>Bavarian Nordic</agency>
        <agency_class>Industry</agency_class>
      </lead_sponsor>
    </sponsors>
    <source>Bavarian Nordic</source>
    <oversight_info>
      <has_dmc>Yes</has_dmc>
      <is_fda_regulated_drug>Yes</is_fda_regulated_drug>
      <is_fda_regulated_device>No</is_fda_regulated_device>
    </oversight_info>
    <brief_summary>
      <textblock>
        The purpose of this phase 3 multicenter, randomized, double-blind, placebo-controlled&#xD;
        rollover study is to evaluate the safety and long-term immunogenicity of PXVX0317 in adult&#xD;
        and adolescent participants and to evaluate PXVX0317 booster vaccine induced serum&#xD;
        neutralizing antibody (SNA) response at 3, 4, or 5 years post-initial PXVX0317 vaccination.&#xD;
      </textblock>
    </brief_summary>
    <detailed_description>
      <textblock>
        Primary Objectives:&#xD;
  &#xD;
          -  To evaluate the long-term immunogenicity of PXVX0317 vaccine in healthy adult and&#xD;
             adolescent participants as measured by proportion of participants maintaining an&#xD;
             anti-CHIKV serum neutralizing antibody (SNA) titer ≥100 (seroresponse rate, also&#xD;
             considered the presumptive seroprotection rate) at yearly intervals up to 5 years&#xD;
             postvaccination in feeder study EBSI-CV-317-004 (NCT05072080).&#xD;
  &#xD;
          -  To assess the vaccine-induced SNA titers by a booster dose of PXVX0317 vaccine at 3, 4,&#xD;
             or 5 years post-initial vaccination in feeder study EBSI-CV- 317-004.&#xD;
  &#xD;
          -  To evaluate the safety and tolerability of PXVX0317 in all participants.&#xD;
  &#xD;
          -  To evaluate the safety and tolerability of a booster vaccination and compare with safety&#xD;
             and tolerability reported post-initial vaccination of PXVX0317 under feeder study&#xD;
             EBSI-CV-317-004 in healthy adults and adolescents.&#xD;
  &#xD;
        Secondary Objectives:&#xD;
  &#xD;
          -  To evaluate the long-term immunogenicity of PXVX0317 vaccine in healthy adult and&#xD;
             adolescent participants as measured by anti-CHIKV SNA geometric mean titers (GMTs) at&#xD;
             yearly intervals up to 5 years post-initial vaccination in feeder study EBSI-CV-317-004.&#xD;
  &#xD;
          -  To evaluate the immune response to a booster vaccination and compare this response to&#xD;
             that reported post-initial vaccination of PXVX0317 under feeder study EBSI-CV-317-004 in&#xD;
             healthy adults and adolescents.&#xD;
      </textblock>
    </detailed_description>
    <overall_status>Not yet recruiting</overall_status>
    <start_date type="Anticipated">August 2023</start_date>
    <completion_date type="Anticipated">May 2028</completion_date>
    <primary_completion_date type="Anticipated">April 2028</primary_completion_date>
    <phase>Phase 3</phase>
    <study_type>Interventional</study_type>
    <has_expanded_access>No</has_expanded_access>
    <study_design_info>
      <allocation>Randomized</allocation>
      <intervention_model>Parallel Assignment</intervention_model>
      <intervention_model_description>Participants still in the study at the Year 3 timepoint (time point relative to initial vaccination in feeder study EBSI-CV-317-004) will be randomized 1:1:1 to Year 3, 4, or 5 and 1:1 to PXVX0317 booster or placebo booster.</intervention_model_description>
      <primary_purpose>Prevention</primary_purpose>
      <masking>Triple (Participant, Care Provider, Investigator)</masking>
      <masking_description>Participants, care providers, and investigator will not be blinded for the timing of when the participant will receive the vaccine booster or placebo booster. They will be blinded to all booster treatment assignments (vaccine booster or placebo booster).</masking_description>
    </study_design_info>
    <primary_outcome>
      <measure>Proportion of participants maintaining an anti-CHIKV SNA titer ≥100 at yearly intervals up to 5 years post-initial vaccination</measure>
      <time_frame>5 years post-initial vaccination in feeder study EBSI-CV-317-004</time_frame>
      <description>For immunogenicity evaluable population (IEP) participants who do not receive a PXVX0317 booster (Groups 1b, 2b, 3b, or Group 4 [unrandomized or unboosted]), proportion of participants maintaining an anti-CHIKV SNA titer ≥100 (seroresponse rate, also considered the presumptive seroprotection rate) at yearly intervals up to 5 years post-initial vaccination in feeder study EBSI-CV-317-004.</description>
    </primary_outcome>
    <primary_outcome>
      <measure>Proportion of vaccine boosted participants with composite booster response at 21 days after booster vaccination</measure>
      <time_frame>21 days after booster vaccination</time_frame>
      <description>For IEP participants who receive a PXVX0317 booster (Groups 1a, 2a, and 3a), proportion of participants with a boost response is defined as a composite of:&#xD;
  ≥4-fold rise in anti-CHIKV SNA titer from prebooster to postbooster measured at 21 days after booster for participants with a prebooster titer ≥100 OR&#xD;
  Anti-CHIKV SNA titer ≥100 and ≥4-fold increase in anti-CHIKV SNA titer from prebooster to postbooster measured at 21 days after booster vaccination for participants with a prebooster titer &lt;100.&#xD;
  Note: Prebooster is the last SNA sample prior to booster dose, ideally the sample on boost day prior to booster dose administration but can be the time point prior if the boost day sample is missed or incorrectly processed.</description>
    </primary_outcome>
    <secondary_outcome>
      <measure>Anti-CHIKV SNA Geometric Mean Titers (GMTs) at yearly intervals</measure>
      <time_frame>5 years post-initial vaccination in feeder study EBSI-CV-317-004</time_frame>
      <description>For all groups using the IEP, anti-CHIKV SNA GMTs at yearly intervals up to 5 years post-initial PXVX0317 vaccination in feeder study EBSI-CV-317-004 and, in Groups 1a, 2a, and 3a (PXVX0317 IEP booster population), at 21 days postboost.</description>
    </secondary_outcome>
    <secondary_outcome>
      <measure>Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) Prebooster to Postbooster</measure>
      <time_frame>21 days after booster vaccination and 5 years post-initial vaccination in feeder study EBSI-CV-317-004</time_frame>
      <description>For IEP participants who receive a PXVX0317 booster (Groups 1a, 2a, and 3a; PXVX0317 IEP booster population) and have a 21-day postbooster SNA titer, GMFI from prebooster anti-CHIKV SNA titer to 21 days postbooster anti-CHIKV SNA titer and at yearly intervals up to 5 years post-initial vaccination in feeder study EBSI-CV-317-004.</description>
    </secondary_outcome>
    <secondary_outcome>
      <measure>Booster Response at 21 Days Relative to 21-day Response in Feeder Study EBSI-CV-317-004</measure>
      <time_frame>21 days after booster vaccination</time_frame>
      <description>For IEP participants who receive a PXVX0317 booster (Groups 1a, 2a, and 3a; PXVX0317 IEP booster population) and have a 21-day postboost SNA titer, GMFI from feeder study EBSI-CV-317-004 Day 22 SNA titer to 21-day postbooster SNA titer in the rollover study.</description>
    </secondary_outcome>
    <other_outcome>
      <measure>Proportion of vaccine boosted participants with local or systemic solicited adverse events (AEs) within 7 days after booster vaccination</measure>
      <time_frame>7 days after booster vaccination</time_frame>
      <description>Proportion of participants with local or systemic solicited AEs of increased frequency or severity after a booster vaccination of PXVX0317 (Groups 1a, 2a, and 3a) as compared with those reported by the same participants after initial vaccination of PXVX0317 under the feeder study (EBSI-CV-317-004) in healthy adults and adolescents.</description>
    </other_outcome>
    <other_outcome>
      <measure>Proportion of vaccine or placebo boosted participants with of unsolicited Adverse Events (AEs)</measure>
      <time_frame>28 days after booster vaccination</time_frame>
      <description>Occurrence of unsolicited AEs within 28 days postbooster (Groups 1, 2, and 3).</description>
    </other_outcome>
    <other_outcome>
      <measure>Proportion of vaccine or placebo boosted participants with of Adverse Events of Special Interest (AESI)</measure>
      <time_frame>5 years post-initial vaccination in the feeder study for Groups 1, 2 and 4; 5.5 years post-initial vaccination in the feeder study for Group 3</time_frame>
      <description>Occurrence of AESI, through the duration of the study for all participants.</description>
    </other_outcome>
    <other_outcome>
      <measure>Proportion of vaccine or placebo boosted participants with Medically Attended Adverse Event (MAAE)</measure>
      <time_frame>5 years post-initial vaccination in the feeder study for Groups 1, 2 and 4; 5.5 years post-initial vaccination in the feeder study for Group 3</time_frame>
      <description>Occurrence of MAAE, through the duration of the study for all participants.</description>
    </other_outcome>
    <other_outcome>
      <measure>Proportion of participants with Serious Adverse Events (SAEs)</measure>
      <time_frame>5 years post-initial vaccination in the feeder study for Groups 1, 2 and 4; 5.5 years post-initial vaccination in the feeder study for Group 3</time_frame>
      <description>Occurrence of SAEs through the duration of the study for all participants.</description>
    </other_outcome>
    <number_of_arms>7</number_of_arms>
    <enrollment type="Anticipated">800</enrollment>
    <condition>Chikungunya Virus Infection</condition>
    <arm_group>
      <arm_group_label>Group 1a</arm_group_label>
      <arm_group_type>Active Comparator</arm_group_type>
      <description>PXVX0317 vaccine booster, 3 years post initial vaccination</description>
    </arm_group>
    <arm_group>
      <arm_group_label>Group 1b</arm_group_label>
      <arm_group_type>Placebo Comparator</arm_group_type>
      <description>Placebo booster, 3 years post initial vaccination</description>
    </arm_group>
    <arm_group>
      <arm_group_label>Group 2a</arm_group_label>
      <arm_group_type>Active Comparator</arm_group_type>
      <description>PXVX0317 vaccine booster, 4 years post initial vaccination</description>
    </arm_group>
    <arm_group>
      <arm_group_label>Group 2b</arm_group_label>
      <arm_group_type>Placebo Comparator</arm_group_type>
      <description>Placebo booster, 4 years post initial vaccination</description>
    </arm_group>
    <arm_group>
      <arm_group_label>Group 3a</arm_group_label>
      <arm_group_type>Active Comparator</arm_group_type>
      <description>PXVX0317 vaccine booster, 5 years post initial vaccination</description>
    </arm_group>
    <arm_group>
      <arm_group_label>Group 3b</arm_group_label>
      <arm_group_type>Placebo Comparator</arm_group_type>
      <description>Placebo booster, 5 years post initial vaccination</description>
    </arm_group>
    <arm_group>
      <arm_group_label>Group 4</arm_group_label>
      <arm_group_type>No Intervention</arm_group_type>
      <description>Unrandomized or unboosted participants, for any reason</description>
    </arm_group>
    <intervention>
      <intervention_type>Biological</intervention_type>
      <intervention_name>PXVX0317 vaccine booster</intervention_name>
      <description>PXVX0317 vaccine is comprised of chikungunya virus virus-like particles (CHIKV VLP) 40mg, aluminum hydroxide 2% adjuvant, and formulation buffer supplied as a single dose of 0.8 mL in a pre-filled syringe, to be administered via intramuscular (IM) injection in the deltoid muscle.</description>
      <arm_group_label>Group 1a</arm_group_label>
      <arm_group_label>Group 2a</arm_group_label>
      <arm_group_label>Group 3a</arm_group_label>
      <other_name>CHIKV VLP</other_name>
    </intervention>
    <intervention>
      <intervention_type>Biological</intervention_type>
      <intervention_name>Placebo booster</intervention_name>
      <description>Placebo is comprised of formulation buffer supplied as a single dose of 0.8 mL in a pre-filled syringe administered via IM injection in the deltoid muscle.</description>
      <arm_group_label>Group 1b</arm_group_label>
      <arm_group_label>Group 2b</arm_group_label>
      <arm_group_label>Group 3b</arm_group_label>
    </intervention>
    <eligibility>
      <criteria>
        <textblock>
          Inclusion Criteria:&#xD;
  &#xD;
            -  Within the feeder study informed consent form (ICF) (and/or assent form, as&#xD;
               applicable), the participant voluntarily signed and agreed to be contacted by the&#xD;
               sponsor for potential screening and enrollment in a future study (ie,&#xD;
               EBSI-CV-317-008).&#xD;
  &#xD;
            -  Able and willing to provide informed consent (and assent, as applicable) voluntarily&#xD;
               signed by participant (and guardian, as applicable) for participation in this rollover&#xD;
               study EBSI-CV-317-008, including possible receipt of a booster dose of PXVX0317.&#xD;
  &#xD;
            -  Males or females, 12 to &lt;65 years of age at the time of enrollment in the feeder&#xD;
               study.&#xD;
  &#xD;
            -  Received a single dose of PXVX0317 vaccine in the feeder study.&#xD;
  &#xD;
            -  Demonstrated compliance to the feeder study conduct (ie, rollover participant was&#xD;
               without protocol deviations that excluded them from analysis in feeder study&#xD;
               EBSI-CV-317-004) without discontinuation or early withdrawal.&#xD;
  &#xD;
            -  Generally healthy, in the opinion of the investigator, based on medical history and&#xD;
               physical examination.&#xD;
  &#xD;
          Additional inclusion criteria to be assessed at Prerandomization Visit (Visit 5) and&#xD;
          Randomization Visit (Visit 6) to determine eligibility for a booster:&#xD;
  &#xD;
          - Women who are either: i. Not of childbearing potential (CBP): premenarche, surgically&#xD;
          sterile (at least six weeks postbilateral tubal ligation or bilateral total salpingectomy,&#xD;
          bilateral oophorectomy, or hysterectomy), or postmenopausal (defined as a history of ≥12&#xD;
          consecutive months without menses prior to randomization in the absence of other pathologic&#xD;
          or physiologic causes, following cessation of exogenous sex-hormonal treatment). For women&#xD;
          who are postmenopausal, documented follicle stimulating hormone (FSH) level of ≥40 mIU/mL&#xD;
          must be obtained. If the FSH is &lt;40 mIU/mL, the participant must agree to use an acceptable&#xD;
          form of contraception. or: ii. Meet all the below criteria:&#xD;
  &#xD;
            -  Negative serum pregnancy test at Prerandomization Visit&#xD;
  &#xD;
            -  Negative urine pregnancy test at Prebooster Visit and immediately prior to booster&#xD;
               dose administration&#xD;
  &#xD;
            -  Use one of these acceptable methods of contraception (if women of CBP) for at least&#xD;
               six months after booster:&#xD;
  &#xD;
            -  Hormonal contraceptives (eg, implants, pills, patches) initiated ≥30 days prior to&#xD;
               booster dose administration&#xD;
  &#xD;
            -  Intrauterine device (IUD) inserted ≥30 days prior to booster dose administration&#xD;
  &#xD;
            -  Double barrier type of birth control (male condom with female diaphragm, male condom&#xD;
               with cervical cap)&#xD;
  &#xD;
            -  Abstinence is acceptable only for adolescents (12-&lt;18 years of age) who are not&#xD;
               sexually active.&#xD;
  &#xD;
          Women participants of CBP must use an acceptable method of contraception from ≥30 days&#xD;
          prior to randomization through six-months postbooster vaccination dose (if applicable).&#xD;
  &#xD;
          Note: Contraception requirements do not apply for participants in exclusively same-sex&#xD;
          relationships and these participants should have no plans to become pregnant by any other&#xD;
          means for the duration of the study. Contraception requirements do not apply to Group 4&#xD;
          participants (unrandomized or unboosted).&#xD;
  &#xD;
          Exclusion Criteria:&#xD;
  &#xD;
            -  Received placebo treatment in the feeder study.&#xD;
  &#xD;
            -  Measurable anti-CHIKV SNA at Day 1 in the feeder study.&#xD;
  &#xD;
            -  History of severe allergic reaction or anaphylaxis to any component of the&#xD;
               investigational product (IP).&#xD;
  &#xD;
            -  Receipt of either an investigational or licensed CHIKV vaccine (excluding prior&#xD;
               receipt of PXVX0317).&#xD;
  &#xD;
            -  New onset/diagnosis of any disease falling within the feeder study exclusion criteria&#xD;
               including: i. History of any known congenital or acquired immunodeficiency that could&#xD;
               impact response to vaccination (eg, leukemia, lymphoma, generalized malignancy,&#xD;
               functional or anatomic asplenia, alcoholic cirrhosis) or ii. Clinically significant&#xD;
               cardiac, pulmonary, rheumatologic, or other chronic disease, in the opinion of the&#xD;
               investigator. This may include chronic illness requiring hospitalization during the&#xD;
               feeder study.&#xD;
  &#xD;
            -  Evidence of substance abuse that, in the opinion of the investigator, could adversely&#xD;
               impact the individual's participation or the conduct of the study.&#xD;
  &#xD;
            -  Any other medical condition or general reason that, in the opinion of the&#xD;
               investigator, could adversely impact the individual's participation or the conduct of&#xD;
               the study.&#xD;
  &#xD;
            -  Participation or planned participation in an investigational clinical trial, excluding&#xD;
               feeder study EBSI-CV-317-004 (eg, vaccine, drug, medical device, or medical procedure)&#xD;
               for the duration of this study. Note: Participation in an observational trial or&#xD;
               follow-up phase of a trial may be allowed; however, these instances should be&#xD;
               discussed with this study's medical monitor (MM).&#xD;
  &#xD;
          Additional exclusion criteria to be assessed at Prerandomization Visit (Visit 5),&#xD;
          Randomization Visit (Visit 6), and Prebooster (for Groups 2 and 3) Visit(s) to determine&#xD;
          eligibility for a booster:&#xD;
  &#xD;
            -  Positive laboratory evidence of current infection with human immunodeficiency virus&#xD;
               (HIV), hepatitis C virus (HCV) or hepatitis B virus (HBV).&#xD;
  &#xD;
            -  Prior receipt or anticipated use of systemic immunomodulatory or immunosuppressive&#xD;
               medications from six months prior to Prebooster Visit through 21 days after booster&#xD;
               dose. Note: For systemic corticosteroids, use at a dose or equivalent dose of 20 mg of&#xD;
               prednisone daily for 14 days or more within three months of Prebooster Visit through&#xD;
               21 days postbooster dose is exclusionary. The use of inhaled, intranasal, topical,&#xD;
               ocular, or intraocular steroids is allowed.&#xD;
  &#xD;
            -  Receipt or anticipated receipt of blood or blood-derived products from 90 days prior&#xD;
               to Prebooster Visit through 21 days postbooster dose.&#xD;
  &#xD;
            -  Acute disease within the last 14 days prior to booster dose (participants with an&#xD;
               acute mild febrile illness can be considered for a deferral of vaccination two weeks&#xD;
               after the illness has resolved and treatment has been completed).&#xD;
  &#xD;
            -  Receipt or anticipated receipt of any vaccine from 30 days prior to booster dose&#xD;
               through 21 days postbooster.&#xD;
  &#xD;
            -  Experienced a related safety event in the feeder study that, in the investigator's&#xD;
               judgement, precludes receipt of booster.&#xD;
  &#xD;
          Note: Participants that are ineligible or decline booster will be included in Group 4&#xD;
          (unrandomized or unboosted) for follow-up unless consent/assent for follow-up is withdrawn.&#xD;
        </textblock>
      </criteria>
      <gender>All</gender>
      <minimum_age>12 Years</minimum_age>
      <maximum_age>67 Years</maximum_age>
      <healthy_volunteers>Accepts Healthy Volunteers</healthy_volunteers>
    </eligibility>
    <overall_official>
      <last_name>Patrick Ajiboye, MD</last_name>
      <role>Study Director</role>
      <affiliation>Bavarian Nordic</affiliation>
    </overall_official>
    <overall_contact>
      <last_name>Sufia Muhammad, MD</last_name>
      <phone>240-631-3573</phone>
      <email>SUMU@bavarian-nordic.com</email>
    </overall_contact>
    <verification_date>August 2023</verification_date>
    <study_first_submitted>August 18, 2023</study_first_submitted>
    <study_first_submitted_qc>August 18, 2023</study_first_submitted_qc>
    <study_first_posted type="Actual">August 23, 2023</study_first_posted>
    <last_update_submitted>August 18, 2023</last_update_submitted>
    <last_update_submitted_qc>August 18, 2023</last_update_submitted_qc>
    <last_update_posted type="Actual">August 23, 2023</last_update_posted>
    <responsible_party>
      <responsible_party_type>Sponsor</responsible_party_type>
    </responsible_party>
    <keyword>Chikungunya</keyword>
    <keyword>PXVX0317</keyword>
    <keyword>Vaccine</keyword>
    <keyword>Immunogenicity</keyword>
    <keyword>CHIKV VLP</keyword>
    <condition_browse>
      <!-- CAUTION:  The following MeSH terms are assigned with an imperfect algorithm            -->
      <mesh_term>Chikungunya Fever</mesh_term>
    </condition_browse>
    <!-- Results have not yet been posted for this study                                          -->
  </clinical_study>
  
  
text: download date: ClinicalTrials.gov processed this data on September 20, 2023
  link text: Link to the current ClinicalTrials.gov record.
  url: https://clinicaltrials.gov/ct2/show/NCT06007183
  org study id: EBSI-CV-317-008
  nct id: NCT06007183
  lead sponsor: 
  has dmc: Yes
  is fda regulated drug: Yes
  is fda regulated device: No
  The purpose of this phase 3 multicenter, randomized, double-blind, placebo-controlled
        rollover study is to evaluate the safety and long-term immunogenicity of PXVX0317 in adult
        and adolescent participants and to evaluate PXVX0317 booster vaccine induced serum
        neutralizing antibody (SNA) response at 3, 4, or 5 years post-initial PXVX0317 vaccination.
  Primary Objectives:
  
          -  To evaluate the long-term immunogenicity of PXVX0317 vaccine in healthy adult and
             adolescent participants as measured by proportion of participants maintaining an
             anti-CHIKV serum neutralizing antibody (SNA) titer ≥100 (seroresponse rate, also
             considered the presumptive seroprotection rate) at yearly intervals up to 5 years
             postvaccination in feeder study EBSI-CV-317-004 (NCT05072080).
  
          -  To assess the vaccine-induced SNA titers by a booster dose of PXVX0317 vaccine at 3, 4,
             or 5 years post-initial vaccination in feeder study EBSI-CV- 317-004.
  
          -  To evaluate the safety and tolerability of PXVX0317 in all participants.
  
          -  To evaluate the safety and tolerability of a booster vaccination and compare with safety
             and tolerability reported post-initial vaccination of PXVX0317 under feeder study
             EBSI-CV-317-004 in healthy adults and adolescents.
  
        Secondary Objectives:
  
          -  To evaluate the long-term immunogenicity of PXVX0317 vaccine in healthy adult and
             adolescent participants as measured by anti-CHIKV SNA geometric mean titers (GMTs) at
             yearly intervals up to 5 years post-initial vaccination in feeder study EBSI-CV-317-004.
  
          -  To evaluate the immune response to a booster vaccination and compare this response to
             that reported post-initial vaccination of PXVX0317 under feeder study EBSI-CV-317-004 in
             healthy adults and adolescents.
  allocation: Randomized
  intervention model: Parallel Assignment
  intervention model description: Participants still in the study at the Year 3 timepoint (time point relative to initial vaccination in feeder study EBSI-CV-317-004) will be randomized 1:1:1 to Year 3, 4, or 5 and 1:1 to PXVX0317 booster or placebo booster.
  primary purpose: Prevention
  masking: Triple (Participant, Care Provider, Investigator)
  masking description: Participants, care providers, and investigator will not be blinded for the timing of when the participant will receive the vaccine booster or placebo booster. They will be blinded to all booster treatment assignments (vaccine booster or placebo booster).
  measure: Proportion of participants maintaining an anti-CHIKV SNA titer ≥100 at yearly intervals up to 5 years post-initial vaccination
  time frame: 5 years post-initial vaccination in feeder study EBSI-CV-317-004
  description: For immunogenicity evaluable population (IEP) participants who do not receive a PXVX0317 booster (Groups 1b, 2b, 3b, or Group 4 [unrandomized or unboosted]), proportion of participants maintaining an anti-CHIKV SNA titer ≥100 (seroresponse rate, also considered the presumptive seroprotection rate) at yearly intervals up to 5 years post-initial vaccination in feeder study EBSI-CV-317-004.
  measure: Proportion of vaccine boosted participants with composite booster response at 21 days after booster vaccination
  time frame: 21 days after booster vaccination
  description: For IEP participants who receive a PXVX0317 booster (Groups 1a, 2a, and 3a), proportion of participants with a boost response is defined as a composite of:
  ≥4-fold rise in anti-CHIKV SNA titer from prebooster to postbooster measured at 21 days after booster for participants with a prebooster titer ≥100 OR
  Anti-CHIKV SNA titer ≥100 and ≥4-fold increase in anti-CHIKV SNA titer from prebooster to postbooster measured at 21 days after booster vaccination for participants with a prebooster titer <100.
  Note: Prebooster is the last SNA sample prior to booster dose, ideally the sample on boost day prior to booster dose administration but can be the time point prior if the boost day sample is missed or incorrectly processed.
  measure: Anti-CHIKV SNA Geometric Mean Titers (GMTs) at yearly intervals
  time frame: 5 years post-initial vaccination in feeder study EBSI-CV-317-004
  description: For all groups using the IEP, anti-CHIKV SNA GMTs at yearly intervals up to 5 years post-initial PXVX0317 vaccination in feeder study EBSI-CV-317-004 and, in Groups 1a, 2a, and 3a (PXVX0317 IEP booster population), at 21 days postboost.
  measure: Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) Prebooster to Postbooster
  time frame: 21 days after booster vaccination and 5 years post-initial vaccination in feeder study EBSI-CV-317-004
  description: For IEP participants who receive a PXVX0317 booster (Groups 1a, 2a, and 3a; PXVX0317 IEP booster population) and have a 21-day postbooster SNA titer, GMFI from prebooster anti-CHIKV SNA titer to 21 days postbooster anti-CHIKV SNA titer and at yearly intervals up to 5 years post-initial vaccination in feeder study EBSI-CV-317-004.
  measure: Booster Response at 21 Days Relative to 21-day Response in Feeder Study EBSI-CV-317-004
  time frame: 21 days after booster vaccination
  description: For IEP participants who receive a PXVX0317 booster (Groups 1a, 2a, and 3a; PXVX0317 IEP booster population) and have a 21-day postboost SNA titer, GMFI from feeder study EBSI-CV-317-004 Day 22 SNA titer to 21-day postbooster SNA titer in the rollover study.
  measure: Proportion of vaccine boosted participants with local or systemic solicited adverse events (AEs) within 7 days after booster vaccination
  time frame: 7 days after booster vaccination
  description: Proportion of participants with local or systemic solicited AEs of increased frequency or severity after a booster vaccination of PXVX0317 (Groups 1a, 2a, and 3a) as compared with those reported by the same participants after initial vaccination of PXVX0317 under the feeder study (EBSI-CV-317-004) in healthy adults and adolescents.
  measure: Proportion of vaccine or placebo boosted participants with of unsolicited Adverse Events (AEs)
  time frame: 28 days after booster vaccination
  description: Occurrence of unsolicited AEs within 28 days postbooster (Groups 1, 2, and 3).
  measure: Proportion of vaccine or placebo boosted participants with of Adverse Events of Special Interest (AESI)
  time frame: 5 years post-initial vaccination in the feeder study for Groups 1, 2 and 4; 5.5 years post-initial vaccination in the feeder study for Group 3
  description: Occurrence of AESI, through the duration of the study for all participants.
  measure: Proportion of vaccine or placebo boosted participants with Medically Attended Adverse Event (MAAE)
  time frame: 5 years post-initial vaccination in the feeder study for Groups 1, 2 and 4; 5.5 years post-initial vaccination in the feeder study for Group 3
  description: Occurrence of MAAE, through the duration of the study for all participants.
  measure: Proportion of participants with Serious Adverse Events (SAEs)
  time frame: 5 years post-initial vaccination in the feeder study for Groups 1, 2 and 4; 5.5 years post-initial vaccination in the feeder study for Group 3
  description: Occurrence of SAEs through the duration of the study for all participants.
  arm group label: Group 1a
  arm group type: Active Comparator
  description: PXVX0317 vaccine booster, 3 years post initial vaccination
  arm group label: Group 1b
  arm group type: Placebo Comparator
  description: Placebo booster, 3 years post initial vaccination
  arm group label: Group 2a
  arm group type: Active Comparator
  description: PXVX0317 vaccine booster, 4 years post initial vaccination
  arm group label: Group 2b
  arm group type: Placebo Comparator
  description: Placebo booster, 4 years post initial vaccination
  arm group label: Group 3a
  arm group type: Active Comparator
  description: PXVX0317 vaccine booster, 5 years post initial vaccination
  arm group label: Group 3b
  arm group type: Placebo Comparator
  description: Placebo booster, 5 years post initial vaccination
  arm group label: Group 4
  arm group type: No Intervention
  description: Unrandomized or unboosted participants, for any reason
  intervention type: Biological
  intervention name: PXVX0317 vaccine booster
  description: PXVX0317 vaccine is comprised of chikungunya virus virus-like particles (CHIKV VLP) 40mg, aluminum hydroxide 2% adjuvant, and formulation buffer supplied as a single dose of 0.8 mL in a pre-filled syringe, to be administered via intramuscular (IM) injection in the deltoid muscle.
  arm group label: Group 1a
  arm group label: Group 2a
  arm group label: Group 3a
  other name: CHIKV VLP
  intervention type: Biological
  intervention name: Placebo booster
  description: Placebo is comprised of formulation buffer supplied as a single dose of 0.8 mL in a pre-filled syringe administered via IM injection in the deltoid muscle.
  arm group label: Group 1b
  arm group label: Group 2b
  arm group label: Group 3b
  criteria: 
  gender: All
  minimum age: 12 Years
  maximum age: 67 Years
  healthy volunteers: Accepts Healthy Volunteers
  last name: Patrick Ajiboye, MD
  role: Study Director
  affiliation: Bavarian Nordic
  last name: Sufia Muhammad, MD
  phone: 240-631-3573
  email: SUMU@bavarian-nordic.com
  responsible party type: Sponsor
  mesh term: Chikungunya Fever