MonkeypoxPhase 2NCT05740982
A Phase 2 Randomized Multisite Trial to Inform Public Health Strategies Involving the Use of MVA-BN Vaccine for Mpox
A Phase 2 study testing JYNNEOS in people with Monkeypox, run by National Institute of Allergy and Infectious Diseases (NIAID) at 18 sites in 2 countries.
Trial summary
This study is a Phase 2 open-label, non-placebo controlled, multi-site clinical trial that will evaluate the standard SC regimen in adolescents ages 12 through 17 years, inclusive, and compared to the standard subcutaneous regimen in adults ages 18 to 50, inclusive. Read more about this study
- Who is it for?
- Ages 12 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Monkeypox
- What is being tested?
- JYNNEOS
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 450 participants
- Where
- 18 sitesin 2 countries
- Study dates
- 22 Mar 2023to 28 Aug 2024
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 50 years
- All sexes
- Healthy volunteers accepted
- Child, Adult
Who may be able to join
- Individuals 18 - 50 years of age inclusive at the time of consent; OR Adolescent ages 12 to 17 years inclusive at the time of consent.
- Adult participant is able to read the written informed consent, states willingness to comply with all study procedures and is anticipated to be available for all study visits; OR Parent(s)/Legal Authorized Representative (LAR)(s) of the participating adolescent is able to read and provides written informed permission and participating adolescent provides assent as appropriate for age or development and approved by IRB. Adolescent states willingness to comply with all study procedures and is anticipated to be available for all study visits.
- . Adult participant is able to understand and agrees to adhere to Lifestyle Considerations during the study; OR Parent(s)/LAR(s) of the participating adolescent is able to understand and states willingness to comply with Lifestyle Considerations.
- Females of reproductive potential who have sexual intercourse with males must agree to use highly effective contraception for at least 1 month prior to signing ICF and through Day 57.
- NOTE: See MOP for definitions and list of acceptable and highly effective methods of contraception
- In good general health as evidenced by medical history, physical examination, and clinical judgement of the investigator to be in stable state of health.
- NOTE: Participants with pre-existing stable chronic medical conditions defined as conditions not requiring significant change in therapy or hospitalization for worsening disease in the 4 weeks prior to enrollment can be included at the discretion of the investigator. This includes stable, well-controlled HIV positive individuals.
- Individuals with HIV must be on suppressive ART for at least 6 months, report a CD4 count of greater than 350 cells/µL and no AIDS-defining illness in the last year.
Who cannot join
- Ever received a licensed or an investigational smallpox or monkeypox vaccine.
- This includes Dryvax, Acam2000, LC 16 m8, MVA-based vaccine candidate or licensed vaccines, and Jynneos, Imvamune or Imvanex)
- Any history of monkeypox, cowpox, or vaccinia infection.
- Close contact of anyone known to have monkeypox in the 3 weeks prior to signing ICF
- Immunocompromised as determined by the investigator
- Recent or current use of any immunosuppressing medications in the 4 weeks prior to signing ICF.
Show all 19Show fewer
- Topical, ophthalmic, inhaled, intranasal and intraarticular corticosteroids are acceptable, but receipt of >/=20 mg/day of prednisone or equivalent for >/=14 consecutive days in the 4 weeks prior to signing ICF is exclusionary.
- Pregnant or breast feeding.
- Received or plans to receive a live vaccine or any COVID-19 vaccine in the 4 weeks before or after each study vaccination.
- Received or plans to receive any other vaccine in the one week before or after each study vaccination.
- Received experimental therapeutic agent or vaccine in the 3 months prior to signing ICF.
- Has known allergy or history of anaphylaxis or other serious adverse reaction to a vaccine or vaccine products.
- This includes individuals with history of severe allergic reaction to gentamicin, ciprofloxacin, chicken or egg protein.
- Has tattoos, scars, or other marks which would, in the opinion of the investigator, interfere with assessment of the vaccination site.
- Has any medical disease or condition that, in the opinion of the participating site PI or appropriate sub-investigator, precludes study participation.
- This includes acute, subacute, intermittent, or chronic medical disease or condition that would place the participant at an unacceptable risk of injury, render the participant unable to meet the requirements of the protocol, or may interfere with the evaluation of responses or the participant's successful completion of this trial.
- Adolescent or adult participant has a history of myocarditis/pericarditis or a history of structural congenital heart defect/cardiac dysrhythmia that, in the opinion of the investigator, poses increased risk to the participant.
- Adolescent or adult participant has a history of COVID-19 (with positive test for SARS-CoV-2) in the 4 weeks prior to receipt of the first study vaccination.
- Note: This includes positive rapid antigen test, polymerase chain reaction (PCR) assay, or other nucleic acid amplification (NAAT) test including those performed by the participant at home.
Trial locations and contacts
18 sites in 2 countries.
18 sites in 2 countries
United States17 sites
Emory University School of Medicine
Atlanta, Georgia, 30322-1014
University of Maryland, School of Medicine, Center for Vaccine Development and Global Health
Baltimore, Maryland, 21201-1509
NIH Clinical Research Center, Investigational Drug Management and Research Section
Bethesda, Maryland, 20892-1504
Children's of Alabama Child Health Research Unit (CHRU)
Birmingham, Alabama, 35233-0011
Brigham and Women's Hospital
Boston, Massachusetts, 02115-6110
Cincinnati Children's Hospital Medical Center Vaccine Research Center
Cincinnati, Ohio, 45229-3039
Duke Vaccine and Trials Unit
Durham, North Carolina, 27703
University of Texas Medical Branch
Galveston, Texas, 77555-0435
Baylor College of Medicine
Houston, Texas, 77030-3411
Vanderbilt University Medical Center
Nashville, Tennessee, 37212
Children's Hospital of Philadelphia
Philadelphia, Pennsylvania, 19146
UPMC University Center
Pittsburgh, Pennsylvania, 15213
University of Rochester Medical Center
Rochester, New York, 14642-0001
Kaiser Permanente Washington Health Research Institute
Seattle, Washington, 98101-1466
Saint Louis University Center for Vaccine Development
St Louis, Missouri, 63104-1015
Washington University in St. Louis
St Louis, Missouri, 63110-1010
George Washington University Medical Faculty Associates
Washington D.C., District of Columbia, 20037
Puerto Rico1 site
Ponce Medical School Foundation Inc., CAIMED Center
Ponce, 00716
About this study
Official title: A Phase 2 Randomized, Open-Label, Multisite Trial to Inform Public Health Strategies Involving the Use of MVA-BN Vaccine for Mpox
This study is a Phase 2 open-label, non-placebo controlled, multi-site clinical trial that will evaluate the standard SC regimen in adolescents ages 12 through 17 years, inclusive, and compared to the standard subcutaneous regimen in adults ages 18 to 50, inclusive. Approximately 135 healthy, vaccinia-naïve adults will be enrolled in a comparator arm (Arm 4) and will be given the standard, licensed regimen of 1x10^8 TCID50 MVA-BN administered SC on Day 1 and 29. These adults (Arm 4) will be combined with the 76 healthy, vaccinia-naïve adults that received the standard SC regimen in Stage 1 (Arm 3). Together, this will be the comparator group for non-inferiority testing for the primary endpoint. Approximately 315 healthy, vaccinia-naïve adolescents will be enrolled and given 1x10^8 TCID50 MVA-BN administered SC on Days 1 and 29 (Arm 5). The study will have a set target enrollment of at least 25% adolescents ages 12 to 14 years, inclusive, to ensure that adequate numbers of younger adolescents are enrolled.
The primary objectives are 1.) to determine if peak (Day 43) humoral immune responses in adolescents ages 12 to 17 years following administration of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC are non-inferior to the response in adults ages 18 to 50 years who received the licensed 2-dose SC regimen of 1 x 10^8 TCID50 MVA-BN ; and 2.) to describe safety of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC in adolescents ages 12 to 17 years.
Read the detailed description
This study is a Phase 2 open-label, non-placebo controlled, multi-site clinical trial that will evaluate to inform public health decisions regarding the use of JYNNEOS for monkey pox prevention and mitigation of outbreaks. In stage 2 of the study, the standard subcutaneous (SC) regimen in adolescents ages 12 through 17 years, inclusive, and compared to the standard SC regimen in adults ages 18 to 50, inclusive. Approximately 135 healthy, vaccinia-naïve adults will be enrolled in a comparator arm (Arm 4) and will be given the standard, licensed regimen of 1x10^8 TCID50 MVA-BN administered SC on Day 1 and 29. These adults (Arm 4) will be combined with the 76 healthy, vaccinia-naïve adults that received the standard SC regimen in Stage 1 (Arm 3). Together, this will be the comparator group for non-inferiority testing for the primary endpoint. Approximately 315 healthy, vaccinia-naïve adolescents will be enrolled and given 1x10^8 TCID50 MVA-BN administered SC on Days 1 and 29 (Arm 5). The study will have a set target enrollment of at least 25% adolescents ages 12 to 14 years, inclusive, to ensure that adequate numbers of younger adolescents are enrolled.
The primary objectives are 1.) to determine if peak (Day 43) humoral immune responses in adolescents ages 12 to 17 years following administration of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC are non-inferior to the response in adults ages 18 to 50 years who received the licensed 2-dose SC regimen of 1 x 108 TCID50 MVA-BN; and 2.) to describe safety of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC in adolescents ages 12 to 17 years. The secondary objectives are 1) to evaluate humoral immune responses at baseline, prior to the second vaccination, and following receipt of the 2-dose SC regimen of 1 x 10^8 TCID50 MVA-BN in adolescents compared to adults on each study day; 2) to evaluate the kinetics of the humoral immune responses to the 2-dose SC regimen of 1 x 10^8 TCID50 MVA-BN in adolescents and adults through Day 365 after the second dose is administered; 3.) to compare relative safety and reactogenicity between adolescent and adult study arms; and 4.) to evaluate seroconversion between adolescent and adult study arms.
- Conditions
- Monkeypox
- Being tested
- JYNNEOS
- Keywords
- Adolescent, Adults, Humoral Immune Response, JYNNEOS, Monkeypox, Mpox, MVA-BN, Non-Inferiority Testing, Non-Randomized, Open-label, Pediatric, Phase 2, Public Health, Vaccine, Vaccinia Naive
- Medical subject headings
- Mpox, Monkeypox
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
JYNNEOSBiological
JYNNEOS is FDA-approved and licensed as a smallpox and monkeypox vaccine in the United States. JYNNEOS is a live vaccine produced from the strain Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN), an attenuated, non-replicating orthopoxvirus.
| Study group | Role | What they receive |
|---|---|---|
| 4 | Active comparator | 0.5 mL of 1 x 10^8 (50% Tissue Culture Infectious Dose (TCID50) JYNNEOS (Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN)) administered subcutaneously on adults ages 18-50 years on Days 1 and 29. N=135 Receives: Biological: JYNNEOS |
| 5 | Experimental | 0.5 mL of 1 x 10^8 (50% Tissue Culture Infectious Dose (TCID50) JYNNEOS (Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN)) administered subcutaneously on adolescents ages 12-17 years on Days 1 and 29. N=315 Receives: Biological: JYNNEOS |
What is being measured
The primary outcome is the main question the study is designed to answer.
Vaccinia Virus Specific Plaque Reduction Neutralization Test (PRNT) Geometric Mean Titer (GMT)
Serum collected at Study Day 43 was assayed via PRNT to determine if humoral immune responses in adolescents ages 12 to 17 years are non-inferior to responses in adults after receipt of a 2-dose subcutaneous regimen of 1 x 10^8 MVA-BN. As the primary analysis, adolescents were compared against a pooled group of adults enrolled in Stage 2 and adults enrolled in Stage 1 who received the same study product regimen. As a sensitivity analysis, adolescents were compared against only adults enrolled in Stage 2.
Measured: Day 43
Number of Adolescents Reporting Solicited Adverse Events (AEs) by Severity
AEs solicited via memory aid provided to participants included fever, chills, nausea, headache, fatigue, change in appetite, myalgia, arthralgia, pain at the injection site, erythema/redness, induration/swelling, and pruritis at the injection site. Participants are considered reporting the AE if they reported mild or greater severity at any time through 7 days after each study vaccination (Days 1-8 for Dose 1 and Days 29-36 for Dose 2). The maximum severity reported by participants for each symptom is presented.
Measured: Day 1 through Day 36
Number of Adolescents Reporting Unsolicited Adverse Events (AEs) by Relationship to Study Product
Frequency of all unsolicited AEs from day of each study vaccination through 28 days after each vaccination (Day 1 through Day 29 for Dose 1 and Day 29 through Day 57 for Dose 2).
Measured: Day 1 through Day 57
Number of Adolescents Reporting Adverse Events of Special Interest (AESIs)
A protocol-specified adverse event of special interest (AESI) is defined as a case of myocarditis or pericarditis. All participants with signs and symptoms of myocarditis/pericarditis (e.g., chest pain, shortness of breath, palpitations, etc.) in whom myocarditis/pericarditis was excluded, or for whom an alternative diagnosis was made, were not be considered a suspect case and as such, not reported as an AESI. All other suspected cases of myocarditis or pericarditis were reported as an AESI and the case adjudicated using the Brighton Collaboration case definitions for myocarditis and pericarditis. The Brighton Collaboration case definitions were used to classify into possible, probable, or definite myocarditis or pericarditis cases.
Measured: Day 1 through Day 210
Number of Adolescents Reporting Medically Attended Adverse Events (MAAEs) Related to Study Product
A medically attended adverse event (MAAE) is defined as an AE with medically attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Adverse events identified at a routine study visit (e.g., abnormal vitals) will not be considered MAAEs.
Measured: Day 1 through Day 210
Number of Adolescents Reporting Serious Adverse Events (SAEs) by Relatedness to Study Product
SAEs included any untoward medical occurrence that resulted in death, a life-threatening adverse event, inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, or a congenital anomaly/birth defect. All SAEs were collected from Day 1 through end of study (Day 394).
Measured: Day 1 through Day 394
Number of Adolescents Who Withdrew From Study or Discontinued Vaccination
Participants could voluntarily withdraw their consent for study participation for any reason at any time. Primary reason for withdrawal was recorded and early termination visits were attempted. Participants who received the first vaccination could choose to discontinue receipt of study vaccine for any reason and could choose to remain in the study (i.e., not withdraw from study). In addition, a participant could be discontinued from receipt of the second vaccination. Discontinuation from vaccination did not mean automatic withdrawal from the study, and participants were monitored for safety and immunogenicity if the participant consented.
Measured: Day 1 through Day 394
Secondary outcomes (9)
Vaccinia Virus Specific Plaque Reduction Neutralization Test (PRNT) Geometric Mean Titer (GMT)
Serum collected at Days 1, 29, 210, and 394 was assayed via PRNT to evaluate humoral immune responses in adolescents ages 12 to 17 years compared to responses in adults after receipt of a 2-dose subcutaneous regimen of 1 x 10^8 MVA-BN.
Measured: Days 1, 29, 210, and 394
Vaccinia Virus Specific PRNT Half-life (t ½)
Half-life, defined as the time from expected peak response (Day 43) to 50% maximal response, was estimated using the first participant visit with titer results less than or equal to half the titer results at Day 43.
Measured: Day 1 through Day 394
Number of Participants Reporting Solicited Adverse Events (AEs) by Severity
AEs solicited via memory aid provided to participants included fever, chills, nausea, headache, fatigue, change in appetite, myalgia, arthralgia, pain at the injection site, erythema/redness, induration/swelling, and pruritis at the injection site. Participants are considered reporting the AE if they reported mild or greater severity at any time through 7 days after each study vaccination (Days 1-8 for Dose 1 and Days 29-36 for Dose 2). The maximum severity reported by participants for each symptom is presented.
Measured: Day 1 through Day 36
Number of Participants Reporting Unsolicited Adverse Events (AEs) by Relationship to Study Product
Frequency of all unsolicited AEs from day of each study vaccination through 28 days after each vaccination (Day 1 through Day 29 for Dose 1 and Day 29 through Day 57 for Dose 2).
Measured: Day 1 through Day 57
Number of Participants Reporting Adverse Events of Special Interest (AESIs)
A protocol-specified adverse event of special interest (AESI) is defined as a case of myocarditis or pericarditis. All participants with signs and symptoms of myocarditis/pericarditis (e.g., chest pain, shortness of breath, palpitations, etc.) in whom myocarditis/pericarditis was excluded, or for whom an alternative diagnosis was made, were not be considered a suspect case and as such, not reported as an AESI. All other suspected cases of myocarditis or pericarditis were reported as an AESI and the case adjudicated using the Brighton Collaboration case definitions for myocarditis and pericarditis. The Brighton Collaboration case definitions were used to classify into possible, probable, or definite myocarditis or pericarditis cases.
Measured: Day 1 through Day 210
Number of Participants Reporting Medically Attended Adverse Events (MAAEs) Related to Study Product
A medically attended adverse event (MAAE) is defined as an AE with medically attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Adverse events identified at a routine study visit (e.g., abnormal vitals) will not be considered MAAEs.
Measured: Day 1 through Day 210
Number of Participants Reporting Serious Adverse Events (SAEs) by Relatedness to Study Product
SAEs included any untoward medical occurrence that resulted in death, a life-threatening adverse event, inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, or a congenital anomaly/birth defect. All SAEs were collected from Day 1 through end of study (Day 394).
Measured: Day 1 through Day 394
Number of Participants Who Withdrew From Study or Discontinued Vaccination
Participants could voluntarily withdraw their consent for study participation for any reason at any time. Primary reason for withdrawal was recorded and early termination visits were attempted. Participants who received the first vaccination could choose to discontinue receipt of study vaccine for any reason and could choose to remain in the study (i.e., not withdraw from study). In addition, a participant could be discontinued from receipt of the second vaccination. Discontinuation from vaccination did not mean automatic withdrawal from the study, and participants were monitored for safety and immunogenicity if the participant consented.
Measured: Day 1 through Day 394
Percentage of Participants With Vaccinia Virus Specific PRNT Seroconversion
Seroconversion for the Vaccinia virus specific plaque reduction neutralization test (PRNT) is defined as any positive result if negative at baseline or a 2-fold increase in antibody titers above baseline if positive at baseline. A positive result is defined as antibody titers = lower limit of detection (LLOD), i.e., a detectable result, and a negative result is defined as antibody titers <LLOD.
Measured: Days 29, 43, 210, and 394
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Feb 2023
- Study start22 Mar 2023
- Primary completion28 Aug 2024
- Study completion28 Aug 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for MonkeypoxStudies of the same condition, open and under way.
- More trials run by National Institute of Allergy and Infectious Diseases (NIAID)The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 450 participants (actual)
Sponsor and investigators
- Sponsor type
- US National Institutes of Health
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05740982
- Sponsor's protocol ID
- 22-0020B
- Status last verified
- 23 Dec 2025
- First submitted
- 13 Feb 2023
- Last updated
- 27 Mar 2026
- Results posted
- Yes, on ClinicalTrials.gov
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 27 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Randomized, Open-Label, Multisite Trial to Inform Public Health Strategies Involving the Use of MVA-BN Vaccine for Mpox
- ClinicalTrials.gov ID
- NCT05740982
- Acronym / sponsor ID
- 22-0020B
- Conditions
- Monkeypox
- Keywords
- Adolescent, Adults, Humoral Immune Response, JYNNEOS, Monkeypox, Mpox, MVA-BN, Non-Inferiority Testing
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 450 participants (actual)
- Lead sponsor
- National Institute of Allergy and Infectious Diseases (NIAID)US National Institutes of Health
- Study start
- 22 Mar 2023 (actual)
- Primary completion
- 28 Aug 2024 (actual)
- Study completion
- 28 Aug 2024 (actual)
- First posted
- 23 Feb 2023 (actual)
- Results
- Posted 27 Mar 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is a Phase 2 open-label, non-placebo controlled, multi-site clinical trial that will evaluate the standard SC regimen in adolescents ages 12 through 17 years, inclusive, and compared to the standard subcutaneous regimen in adults ages 18 to 50, inclusive. Approximately 135 healthy, vaccinia-naïve adults will be enrolled in a comparator arm (Arm 4) and will be given the standard, licensed regimen of 1x10^8 TCID50 MVA-BN administered SC on Day 1 and 29. These adults (Arm 4) will be combined with the 76 healthy, vaccinia-naïve adults that received the standard SC regimen in Stage 1 (Arm 3). Together, this will be the comparator group for non-inferiority testing for the primary endpoint. Approximately 315 healthy, vaccinia-naïve adolescents will be enrolled and given 1x10^8 TCID50 MVA-BN administered SC on Days 1 and 29 (Arm 5). The study will have a set target enrollment of at least 25% adolescents ages 12 to 14 years, inclusive, to ensure that adequate numbers of younger adolescents are enrolled.
The primary objectives are 1.) to determine if peak (Day 43) humoral immune responses in adolescents ages 12 to 17 years following administration of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC are non-inferior to the response in adults ages 18 to 50 years who received the licensed 2-dose SC regimen of 1 x 10^8 TCID50 MVA-BN ; and 2.) to describe safety of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC in adolescents ages 12 to 17 years.
Detailed description
This study is a Phase 2 open-label, non-placebo controlled, multi-site clinical trial that will evaluate to inform public health decisions regarding the use of JYNNEOS for monkey pox prevention and mitigation of outbreaks. In stage 2 of the study, the standard subcutaneous (SC) regimen in adolescents ages 12 through 17 years, inclusive, and compared to the standard SC regimen in adults ages 18 to 50, inclusive. Approximately 135 healthy, vaccinia-naïve adults will be enrolled in a comparator arm (Arm 4) and will be given the standard, licensed regimen of 1x10^8 TCID50 MVA-BN administered SC on Day 1 and 29. These adults (Arm 4) will be combined with the 76 healthy, vaccinia-naïve adults that received the standard SC regimen in Stage 1 (Arm 3). Together, this will be the comparator group for non-inferiority testing for the primary endpoint. Approximately 315 healthy, vaccinia-naïve adolescents will be enrolled and given 1x10^8 TCID50 MVA-BN administered SC on Days 1 and 29 (Arm 5). The study will have a set target enrollment of at least 25% adolescents ages 12 to 14 years, inclusive, to ensure that adequate numbers of younger adolescents are enrolled.
The primary objectives are 1.) to determine if peak (Day 43) humoral immune responses in adolescents ages 12 to 17 years following administration of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC are non-inferior to the response in adults ages 18 to 50 years who received the licensed 2-dose SC regimen of 1 x 108 TCID50 MVA-BN; and 2.) to describe safety of a 2-dose 1 x 10^8 TCID50 MVA-BN regimen administered SC in adolescents ages 12 to 17 years. The secondary objectives are 1) to evaluate humoral immune responses at baseline, prior to the second vaccination, and following receipt of the 2-dose SC regimen of 1 x 10^8 TCID50 MVA-BN in adolescents compared to adults on each study day; 2) to evaluate the kinetics of the humoral immune responses to the 2-dose SC regimen of 1 x 10^8 TCID50 MVA-BN in adolescents and adults through Day 365 after the second dose is administered; 3.) to compare relative safety and reactogenicity between adolescent and adult study arms; and 4.) to evaluate seroconversion between adolescent and adult study arms.
Study design
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| 4 | Active comparator | Biological: JYNNEOS0.5 mL of 1 x 10^8 (50% Tissue Culture Infectious Dose (TCID50) JYNNEOS (Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN)) administered subcutaneously on adults ages 18-50 years on Days 1 and 29. N=135 |
| 5 | Experimental | Biological: JYNNEOS0.5 mL of 1 x 10^8 (50% Tissue Culture Infectious Dose (TCID50) JYNNEOS (Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN)) administered subcutaneously on adolescents ages 12-17 years on Days 1 and 29. N=315 |
Who may qualify
- Ages
- 12 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
Key inclusion criteria (8 listed)
- Individuals 18 - 50 years of age inclusive at the time of consent; OR Adolescent ages 12 to 17 years inclusive at the time of consent.
- Adult participant is able to read the written informed consent, states willingness to comply with all study procedures and is anticipated to be available for all study visits; OR Parent(s)/Legal Authorized Representative (LAR)(s) of the participating adolescent is able to read and provides written informed permission and participating adolescent provides assent as appropriate for age or development and approved by IRB. Adolescent states willingness to comply with all study procedures and is anticipated to be available for all study visits.
- . Adult participant is able to understand and agrees to adhere to Lifestyle Considerations during the study; OR Parent(s)/LAR(s) of the participating adolescent is able to understand and states willingness to comply with Lifestyle Considerations.
- Females of reproductive potential who have sexual intercourse with males must agree to use highly effective contraception for at least 1 month prior to signing ICF and through Day 57.
- NOTE: See MOP for definitions and list of acceptable and highly effective methods of contraception
Key exclusion criteria (19 listed)
- Ever received a licensed or an investigational smallpox or monkeypox vaccine.
- This includes Dryvax, Acam2000, LC 16 m8, MVA-based vaccine candidate or licensed vaccines, and Jynneos, Imvamune or Imvanex)
- Any history of monkeypox, cowpox, or vaccinia infection.
- Close contact of anyone known to have monkeypox in the 3 weeks prior to signing ICF
- Immunocompromised as determined by the investigator
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| JYNNEOSJYNNEOS is FDA-approved and licensed as a smallpox and monkeypox vaccine in the United States. JYNNEOS is a live vaccine produced from the strain Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN), an attenuated, non-replicating orthopoxvirus. | Biological | 4, 5 |
Primary outcome
Vaccinia Virus Specific Plaque Reduction Neutralization Test (PRNT) Geometric Mean Titer (GMT)
Time frame: Day 43
Serum collected at Study Day 43 was assayed via PRNT to determine if humoral immune responses in adolescents ages 12 to 17 years are non-inferior to responses in adults after receipt of a 2-dose subcutaneous regimen of 1 x 10^8 MVA-BN. As the primary analysis, adolescents were compared against a pooled group of adults enrolled in Stage 2 and adults enrolled in Stage 1 who received the same study product regimen. As a sensitivity analysis, adolescents were compared against only adults enrolled in Stage 2.
Number of Adolescents Reporting Solicited Adverse Events (AEs) by Severity
Time frame: Day 1 through Day 36
AEs solicited via memory aid provided to participants included fever, chills, nausea, headache, fatigue, change in appetite, myalgia, arthralgia, pain at the injection site, erythema/redness, induration/swelling, and pruritis at the injection site. Participants are considered reporting the AE if they reported mild or greater severity at any time through 7 days after each study vaccination (Days 1-8 for Dose 1 and Days 29-36 for Dose 2). The maximum severity reported by participants for each symptom is presented.
Number of Adolescents Reporting Unsolicited Adverse Events (AEs) by Relationship to Study Product
Time frame: Day 1 through Day 57
Frequency of all unsolicited AEs from day of each study vaccination through 28 days after each vaccination (Day 1 through Day 29 for Dose 1 and Day 29 through Day 57 for Dose 2).
Number of Adolescents Reporting Adverse Events of Special Interest (AESIs)
Time frame: Day 1 through Day 210
A protocol-specified adverse event of special interest (AESI) is defined as a case of myocarditis or pericarditis. All participants with signs and symptoms of myocarditis/pericarditis (e.g., chest pain, shortness of breath, palpitations, etc.) in whom myocarditis/pericarditis was excluded, or for whom an alternative diagnosis was made, were not be considered a suspect case and as such, not reported as an AESI. All other suspected cases of myocarditis or pericarditis were reported as an AESI and the case adjudicated using the Brighton Collaboration case definitions for myocarditis and pericarditis. The Brighton Collaboration case definitions were used to classify into possible, probable, or definite myocarditis or pericarditis cases.
Number of Adolescents Reporting Medically Attended Adverse Events (MAAEs) Related to Study Product
Time frame: Day 1 through Day 210
A medically attended adverse event (MAAE) is defined as an AE with medically attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Adverse events identified at a routine study visit (e.g., abnormal vitals) will not be considered MAAEs.
Number of Adolescents Reporting Serious Adverse Events (SAEs) by Relatedness to Study Product
Time frame: Day 1 through Day 394
SAEs included any untoward medical occurrence that resulted in death, a life-threatening adverse event, inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, or a congenital anomaly/birth defect. All SAEs were collected from Day 1 through end of study (Day 394).
Number of Adolescents Who Withdrew From Study or Discontinued Vaccination
Time frame: Day 1 through Day 394
Participants could voluntarily withdraw their consent for study participation for any reason at any time. Primary reason for withdrawal was recorded and early termination visits were attempted. Participants who received the first vaccination could choose to discontinue receipt of study vaccine for any reason and could choose to remain in the study (i.e., not withdraw from study). In addition, a participant could be discontinued from receipt of the second vaccination. Discontinuation from vaccination did not mean automatic withdrawal from the study, and participants were monitored for safety and immunogenicity if the participant consented.
9 secondary outcomes
Vaccinia Virus Specific Plaque Reduction Neutralization Test (PRNT) Geometric Mean Titer (GMT)
Time frame: Days 1, 29, 210, and 394
Vaccinia Virus Specific PRNT Half-life (t ½)
Time frame: Day 1 through Day 394
Number of Participants Reporting Solicited Adverse Events (AEs) by Severity
Time frame: Day 1 through Day 36
Number of Participants Reporting Unsolicited Adverse Events (AEs) by Relationship to Study Product
Time frame: Day 1 through Day 57
Number of Participants Reporting Adverse Events of Special Interest (AESIs)
Time frame: Day 1 through Day 210
Number of Participants Reporting Medically Attended Adverse Events (MAAEs) Related to Study Product
Time frame: Day 1 through Day 210
Number of Participants Reporting Serious Adverse Events (SAEs) by Relatedness to Study Product
Time frame: Day 1 through Day 394
Number of Participants Who Withdrew From Study or Discontinued Vaccination
Time frame: Day 1 through Day 394
Percentage of Participants With Vaccinia Virus Specific PRNT Seroconversion
Time frame: Days 29, 43, 210, and 394
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 27 Mar 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- MPox Vaccination Study Survey for adolescent participants interested in enrolling at the University of Rochester Medical CenterLink provided by the sponsor.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
18 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing JYNNEOS in people with Monkeypox, run by National Institute of Allergy and Infectious Diseases (NIAID) at 18 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 19 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 27 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 18 sites in United States, Puerto Rico. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 27 Mar 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Vaccinia Virus Specific Plaque Reduction Neutralization Test (PRNT) Geometric Mean Titer (GMT) (time frame: Day 43). The study lists 7 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 27 Mar 2026.