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Mpox (Monkeypox)Phase 2NCT07379580

A Randomized Clinical Trial Investigating the Safety, Reactogenicity, and Immunogenicity After Immunization With an mRNA-based Mpox Vaccine Candidate in Africa

A Phase 2 study testing BNT166a in people with Mpox (Monkeypox) and Smallpox, run by BioNTech SE at 6 sites in 2 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

This is a randomized, double-blind, placebo-controlled study which aims to assess the safety, reactogenicity, and immunogenicity after one and two doses of BNT166a or placebo in healthy participants. Read more about this study

Who is it for?
Ages 18 to 64 yearsHealthy volunteers can take part
What is being tested?
BNT166a
Type of treatment
Injection or infusion
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
310 participants
Where
6 sitesin 2 countries
Study dates
20 Feb 2026to Jun 2027
Phase
Phase 2
Are there results?
Not yet: the study is under way

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 18 to 64 years
  • All sexes
  • Healthy volunteers accepted
  • Adult

Key Inclusion Criteria (applicable to all participants unless otherwise specified):

  • Are male or female individuals ≥18 years of age at the time of giving informed consent:
  • Cohort 1: ≥18 to ≤45 years of age
  • Cohort 2: ≥18 to ≤64 years of age
  • Cohort 1: Participants must be Orthopoxvirus-naïve (have no history of smallpox or mpox vaccination or mpox infection).
  • Cohort 2: Participants must be Orthopoxvirus-experienced (have evidence of mpox or smallpox vaccination or mpox infection at least 2 years prior to consent).

Key Exclusion Criteria (applicable to all participants unless otherwise specified):

  • Have had recent exposure to mpox (defined as close contact with a probable or confirmed case of mpox within the past 28 days, or have evidence of mpox infection or mpox vaccination within 2 years prior to consent).
  • Have a contraindication, warning and/or precaution to vaccination with a messenger ribonucleic acid (mRNA) Coronavirus disease 2019 (COVID-19) vaccine as specified in the Summary of Product Characteristics for BNT162b2 (COMIRNATY United States Prescribing Information/European Union Summary of Product Characteristics) and BNT166 Investigator Brochure.
  • Have a history of allergies, hypersensitivities, or intolerance to the study treatments including any excipients thereof.
  • Have a current or history of cardiovascular diseases, e.g., myocarditis, pericarditis, myocardial infarction, congestive heart failure, cardiomyopathy, or clinically significant arrhythmias.
  • Have any known bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection.
  • Have a body mass index ≤18.5 kg/m^2 or ≥35 kg/m^2.

NOTE: Other protocol defined Inclusion/Exclusion criteria apply.

Trial locations and contacts

6 sites in 2 countries. Contact the study team or a site near you to ask about taking part.

BioNTech clinical trials patient information contact

+49 6131 9084 ext. 0

patients@biontech.de

6 sites in 2 countries

South Africa4 sites, 4 recruiting

  • TASK Applied Science

    Cape Town, 7405

    Recruiting

  • TREAD Research Pty Ltd

    Cape Town, 7530

    Recruiting

  • Desmond Tutu Health Foundation Masiphumelele Clinic

    Cape Town, 7975

    Recruiting

  • Perinatal HIV Research Unit

    Johannesburg, 1864

    Recruiting

Other trials in South Africa

Democratic Republic of the Congo2 sites, 2 recruiting

  • University of Kinshasa UNIKIN

    Kinshasa, 01306

    Recruiting

  • Institute National de Recherche Biomedicale

    Kinshasa, 5345

    Recruiting

Other trials in Democratic Republic of the Congo

About this study

Official title: Safety, Reactogenicity, and Immunogenicity of an Mpox mRNA Vaccine Candidate, BNT166a, in Healthy Participants Aged 18 Years and Older in African Countries: A Randomized, Double-blind, Placebo-controlled Phase II Trial

This is a randomized, double-blind, placebo-controlled study which aims to assess the safety, reactogenicity, and immunogenicity after one and two doses of BNT166a or placebo in healthy participants.

Read the detailed description

This study will include the following cohorts:

  • Cohort 1: healthy adults aged 18 to 45 years inclusive who are Orthopoxvirus-naïve.
  • Cohort 2: healthy adults aged 18 to 64 years inclusive who are Orthopoxvirus-experienced.

All participants will receive two doses of BNT166a or placebo at least 28 days apart.

The planned study duration per participant is ~14 months.

Being tested
BNT166a, Placebo
Keywords
Monkeypox virus (MPXV), Active immunization, Ribonucleic acid (RNA) vaccine
Medical subject headings
Mpox, Monkeypox, Smallpox, Poxviridae Infections

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • BNT166aBiological

    Intramuscular injection. Injections should be given in the deltoid muscle, using the same non-dominant arm for all IMP doses.

  • PlaceboOther

    Intramuscular injection. Injections should be given in the deltoid muscle, using the same non-dominant arm for all IMP doses.

Study groups in NCT07379580
Study groupRoleWhat they receive
Cohort 1 - BNT166a Dose Level (DL) 1 (Orthopoxvirus-naïve participants, aged 18-45 years)ExperimentalTwo doses of investigational medicinal product (IMP).
Receives: Biological: BNT166a
Cohort 1 - BNT166a DL 2 (Orthopoxvirus-naïve participants, aged 18-45 years)ExperimentalTwo doses of IMP.
Receives: Biological: BNT166a
Cohort 1 - Placebo (Orthopoxvirus-naïve participants, aged 18-45 years)Placebo comparator0.9% sodium chloride solution. Two doses of IMP.
Receives: Other: Placebo
Cohort 2 - BNT166a DL 1 (Orthopoxvirus-experienced participants, aged 18-64 years)ExperimentalTwo doses of IMP.
Receives: Biological: BNT166a
Cohort 2 - BNT166a DL 2 (Orthopoxvirus-experienced participants, aged 18-64 years)ExperimentalTwo doses of IMP.
Receives: Biological: BNT166a
Cohort 2 - Placebo (Orthopoxvirus-experienced participants, aged 18-64 years)Placebo comparator0.9% sodium chloride solution. Two doses of IMP.
Receives: Other: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Number (and percentage) of participants with at least one solicited local reaction (pain, erythema/redness, induration/swelling)

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: For up to 7 days following each dose

  2. Number (and percentage) of participants with at least one solicited systemic reaction (fever, headache, fatigue/tiredness, muscle pain/myalgia, joint pain/arthralgia, chills, diarrhea, vomiting)

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: For up to 7 days following each dose

  3. Number (and percentage) of participants with at least one use of antipyretics/analgesics

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: For up to 7 days following each dose

  4. Number (and percentage) of participants with at least one unsolicited adverse event (AE) (post-Dose 1)

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: From Dose 1 to 28 days post-Dose 1

  5. Number (and percentage) of participants with at least one unsolicited AE (post-Dose 2)

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: From Dose 2 to 28 days post-Dose 2

  6. Number (and percentage) of participants with at least one serious adverse event

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: From Dose 1 until the end of study, i.e., up to ~14 months

  7. Number (and percentage) of participants with at least one AE of special interest

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: From Dose 1 until the end of study, i.e., up to ~14 months

  8. Number (and percentage) of participants with at least one medically attended AE

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: From Dose 1 until the end of study, i.e., up to ~14 months

  9. Number (and percentage) of participants with at least one AE leading to a participant's withdrawal from the study

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Measured: From Dose 1 until the end of study, i.e., up to ~14 months

Secondary outcomes (6)

  1. Geometric mean titers (GMT) of BNT166a antigen-specific (A35, B6, H3, and M1) binding antibody titers

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults, at the defined timepoints.

    Measured: At baseline, 1 month post-Dose 1, and 1 month post- Dose 2

  2. Geometric mean fold rise (GMFR) of BNT166a antigen-specific (A35, B6, H3, and M1) binding antibody titers

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Ratio post-baseline/baseline at the defined timepoints.

    Measured: At 1 month post-Dose 1 and 1 month post-Dose 2

  3. GMT of MPXV-specific neutralizing antibody titers

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults, at the defined timepoints.

    Measured: At baseline, 1 month post-Dose 1, and 1 month post-Dose 2

  4. GMFR of MPXV-specific neutralizing antibody titers

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Ratio post-baseline/baseline at the defined timepoints.

    Measured: At 1 month post-Dose 1 and 1 month post-Dose 2

  5. GMT of vaccinia virus (VACV)-specific neutralizing antibody titers

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults, at the defined timepoints.

    Measured: At baseline, 1 month post-Dose 1, and 1 month post-Dose 2

  6. GMFR of VACV-specific neutralizing antibody titers

    At each dose level of BNT166a in Orthopoxvirus-naïve (Cohort 1) and Orthopoxvirus-experienced (Cohort 2) adults.

    Ratio post-baseline/baseline at the defined timepoints.

    Measured: At 1 month post-Dose 1 and 1 month post-Dose 2

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted30 Jan 2026
  2. Study start20 Feb 2026
  3. Primary completionJun 2027 (estimated)
  4. Study completionJun 2027 (estimated)

Resources

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
Randomised
Intervention model
Parallel groups
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
310 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07379580
Sponsor's protocol ID
BNT166-02
Status last verified
Aug 2026
First submitted
23 Jan 2026
Last updated
11 Aug 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing BNT166a in people with Mpox (Monkeypox) and Smallpox, run by BioNTech SE at 6 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?

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: looking for participants now, as of the sponsor's last update on 11 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 6 sites in South Africa, Democratic Republic of the Congo. 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. Some participants in this study may receive a placebo. 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?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact BioNTech clinical trials patient information (+49 6131 9084 ext. 0, patients@biontech.de), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number (and percentage) of participants with at least one solicited local reaction (pain, erythema/redness, induration/swelling) (time frame: For up to 7 days following each dose). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07379580.

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 11 Aug 2026.

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