Rabies (Healthy Volunteers)Phase 3BAZOOKA_221NCT07455318
Boostability Assessment of Three Rabies Pre-Exposure Regimens in Healthy Volunteers 5 Years Following Priming.
A Phase 3 study testing Booster vaccination in people with Rabies (Healthy Volunteers), run by Institute of Tropical Medicine, Belgium at 6 sites in Belgium.
Trial summary
A multicentre, open label trial in healthy volunteers to assess the boostability of three different rabies pre-exposure prophylaxis regimens (2 x 1IM regimen, 2 x 2 ID regimen, 1 x 2 ID regimen) when administering a single-dose, intramuscular vaccination as simulated post-exposure prophylaxis at least five years… Read more about this study
- Who is it for?
- Ages 18 to 60 years
- Conditions the study is for
- Rabies (Healthy Volunteers)
- What is being tested?
- Booster vaccination
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 561 participants
- Where
- 6 sitesBelgium
- Study dates
- 15 May 2026to Jun 2027
- Phase
- Phase 3
- 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 60 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- ≥ 18 to ≤ 60 years of age at time of inclusion
- Willingness to provide written informed consent
- Having received PrEP with a 21IM, 2²ID or 1²ID regimen at least 5 years before starting the study. For 21IM and 2²ID interval of 5 days to 56 days between the 2 visits is allowed.
Who cannot join
- Known allergy to one of the components of the vaccine.
- Subjects, who received immunomodulating therapy within the last 3 months (12 weeks).
- Note: See Section 6.3 for detailed guidance on immunomodulating therapies.
- Planned vaccination with any inactivated vaccine within 2 weeks before or after vaccination in the study or with any live attenuated vaccine within 1 month before or after each vaccination in the study.
- Ongoing pregnancy or active child wish at the time of booster vaccination (D0).
- Any other PrEP rabies vaccine schedule/vaccination than mentioned in the inclusion criteria.
- Previous rabies (s)PEP
- Inability or unwillingness to comply with study procedures, including protocol-defined visits, assessments, or interventions.
Trial locations and contacts
6 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Clinical Trial Unit Clinical Trial Unit Insitute of Tropical Medicine Antwerp, MsC contact
6 sites in 1 country
Belgium6 sites
Clinical Trial Site Insitute of Tropical Medicine
Antwerp, 2000
Cliniques Universitaires de Saint Luc
Brussels, 1200
Centrum voor vaccinologie (CEVAC)
Ghent, 9000
UZ Brussel
Jette, 1090
Centre Hospitalier Universitaire de Liège
Liège, 4000
Military Hospital Queen Astrid
Neder-Over-Heembeek, 1120
About this study
Official title: A Multicentre, Open-label Trial in Healthy Volunteers to Assess the Boostability of Three Different Rabies Pre-exposure Prophylaxis Regimens When Administering a Single-dose, Intramuscular Vaccination as Simulated Post-exposure Prophylaxis at Least Five Years Following Priming.
A multicentre, open label trial in healthy volunteers to assess the boostability of three different rabies pre-exposure prophylaxis regimens (2 x 1IM regimen, 2 x 2 ID regimen, 1 x 2 ID regimen) when administering a single-dose, intramuscular vaccination as simulated post-exposure prophylaxis at least five years following priming.
Read the detailed description
This multicentre clinical trial will include 561 participants, allocated evenly across 3 groups (187 per group). Participants are assigned to one of three groups according to their prior PrEP regimen, provided their last dose was given at least 5 years prior to enrollment.
- Group 1: 21IM regimen, (N = 187): received PrEP at least 5 years ago through 1 x 1,0 mL IM injection (Day 0 and Day 7), with a 7-day interval between visits (interval of 5 to 56 days is allowed).
- Group 2: 2²ID regimen (N = 187): received PrEP at least 5 years ago through 2 x 0,1 mL ID injections (Day 0 and Day 7) with a 7-day interval between visits (interval of 5 to 56 days is allowed).
- Group 3: 1²ID regimen (N = 187): received PrEP at least 5 years ago through 2 x 0,1 mL ID injections on Day 0
All subjects will receive 1 x 1,0 mL IM injection of purified chick-embryo cell-culture rabies vaccine as sPEP (booster) at least five years after primary vaccination (PrEP).
Neutralizing antibody titers against rabies virus will be measured using the Rapid Fluorescent Focus Inhibition Test (RFFIT) on Day 0 (before administration of sPEP) and on Days 7 and 14 after sPEP vaccination.
A titre of ≥ 0.5 IU/mL is defined as adequate (WHO standard).
- Conditions
- Rabies (Healthy Volunteers)
- Being tested
- Booster vaccination
- Keywords
- Rabies, Vaccination regimens, rabies pre-exposure prophylaxis, boostability, prophylaxis, vaccination
- Medical subject headings
- Rabies
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Booster vaccinationBiological
To investigate whether the boostability of a (A) two-visit IM, (B) two-visit ID and (C) one-visit ID pre-exposure vaccination regimen is non-inferior to a theoretical 99% boostability by administering a single-dose IM booster to simulate exposure to rabies at least 5 years after the pre-exposure regimens regimen.
| Study group | Role | What they receive |
|---|---|---|
| Group 1: 2 x 1IM regimen, (N = 187): | Experimental | Healthy volunteers that received Pre-Exposure Prohphylaxis (PrEP) (a rabies vaccination) at least 5 years ago through 1 x 1,0 mL IM injection (Day 0 and Day 7), with a 7-day interval between visits (interval of 5 to 56 days is allowed). Receives: Biological: Booster vaccination |
| Group 2: 2²ID regimen (N = 187): | Experimental | Received PrEP vaccination (Pre-Exposure prophylaxis usinga rabies vaccine) at least 5 years ago through 2 x 0,1 mL ID injections (Day 0 and Day 7) with a 7-day interval between visits (interval of 5 to 56 days is allowed). Receives: Biological: Booster vaccination |
| Group 3: 1²ID regimen (N = 187) | Experimental | received PrEP (Pre-Exposure prophylaxis using a rabies vaccine) at least 5 years ago through 2 x 0,1 mL ID injections on Day 0 Receives: Biological: Booster vaccination |
What is being measured
The primary outcome is the main question the study is designed to answer.
Primary: boostability
To investigate whether the boostability of a (A) two-visit IM, (B) two-visit ID and (C) one-visit ID Pre-exposure Prophylaxis (PrEP) regimen is non-inferior to a theoretical 99% boostability when a single-dose IM simulated Post Exposure Prophylaxis (sPEP) is administered at least 5 years after the PrEP regimen.
Primary Endpoint: Proportion of participants that have an adequate immune response (Rapid Fluorescent Focus Inhibition Test (RFFIT) level, WHO standard) on Day 7 after the booster.
Measured: 13 months - from First Patient In (FPI) to Last Patient Out (LPO)
Secondary outcomes (7)
RFFIT levels ≥ 0.5 IU/mL Day 14
To estimate per arm the proportion of participant with adequate immune response on Day 14 after the booster. RFFIT levels ≥ 0.5 IU/mL is the WHO standard for adequate immune response.
Measured: 14 days following booster vaccination
FFIT levels ≥ 0.5 IU/mL on the day of the booster (Day 0).
To estimate per arm the proportion of participant with RFFIT levels ≥ 0.5 IU/mL on the day of the booster (Day 0). RFFIT levels ≥ 0.5 IU/mL is the WHO standard for adequate immune response.
Measured: Day 0 - on day of booster vaccination
RFFIT levels ≥ 3.0 IU/mL on Day 7 after the booster
To estimate per arm the proportion of participant with RFFIT levels ≥ 3.0 IU/mL on Day 7 after the booster. A titre ≥ 3.0 IU/ml is considered to be a proxy for good/robust protection.
Measured: Day 7 - following booster vaccination
RFFIT levels ≥ 3.0 IU/mL on Day 14 after the booster.
To estimate per arm the proportion of participants with RFFIT levels ≥ 3.0 IU/mL on Day 14 after the booster. A titre ≥ 3.0 IU/ml is considered to be a proxy for good/robust protection.
Measured: Day 14 after the booster vaccination
RFFIT levels ≥ 10 IU/mL on Day 7 after the booster.
To estimate per arm the proportion of participants with RFFIT levels ≥ 10 IU/mL on Day 7 after the booster. A titre ≥ 10 IU/ml is considered to be a proxy for long-lasting immunity.
Measured: Day 14 following the booster vaccination
RFFIT levels ≥ 10 IU/mL on Day 14 after the booster.
To estimate per arm the proportion of participants with RFFIT levels ≥ 10 IU/mL on Day 14 after the booster. A titre ≥ 10 IU/ml is considered to be a proxy for long-lasting immunity.
Measured: Day 14 following the booster vaccination.
Safety objectives
Safety objectives
- To estimate the proportion of solicited AEs (local reactions and general symptoms) occurring within 7 days after the sPEP vaccination session.
- To estimate the proportion of unsolicited AEs occurring within 7 days after the sPEP vaccination session.
- To estimate the proportion of Severe Adverse Events (SAE) occurring throughout the study period after sPEP vaccination session.
Measured: 1. & 2. Day 7 following the booster vaccination. 3. 13 months - entire study duration FPI to LPO
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Mar 2026
- Study start15 May 2026 (estimated)
- Primary completionJun 2027 (estimated)
- Study completionJun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Rabies (Healthy Volunteers)Studies of the same condition, open and under way.
- 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 3
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 561 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Institute of Tropical Medicine, Belgium
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07455318
- Sponsor's protocol ID
- BAZOOKA_221
- Other IDs
- 2025-524765-24-00, 2025
- Acronym
- BAZOOKA_221
- Status last verified
- Mar 2026
- First submitted
- 23 Feb 2026
- Last updated
- 6 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Multicentre, Open-label Trial in Healthy Volunteers to Assess the Boostability of Three Different Rabies Pre-exposure Prophylaxis Regimens When Administering a Single-dose, Intramuscular Vaccination as Simulated Post-exposure Prophylaxis at Least Five Years Following Priming.
- ClinicalTrials.gov ID
- NCT07455318
- Acronym / sponsor ID
- BAZOOKA_221 / BAZOOKA_221
- Conditions
- Rabies (Healthy Volunteers)
- Keywords
- Rabies, Vaccination regimens, rabies pre-exposure prophylaxis, boostability, prophylaxis, vaccination
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 561 participants (estimated)
- Lead sponsor
- Institute of Tropical Medicine, BelgiumUniversity, hospital or other
- Study start
- 15 May 2026 (estimated)
- Primary completion
- Jun 2027 (estimated)
- Study completion
- Jun 2027 (estimated)
- First posted
- 6 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A multicentre, open label trial in healthy volunteers to assess the boostability of three different rabies pre-exposure prophylaxis regimens (2 x 1IM regimen, 2 x 2 ID regimen, 1 x 2 ID regimen) when administering a single-dose, intramuscular vaccination as simulated post-exposure prophylaxis at least five years following priming.
Detailed description
This multicentre clinical trial will include 561 participants, allocated evenly across 3 groups (187 per group). Participants are assigned to one of three groups according to their prior PrEP regimen, provided their last dose was given at least 5 years prior to enrollment.
- Group 1: 21IM regimen, (N = 187): received PrEP at least 5 years ago through 1 x 1,0 mL IM injection (Day 0 and Day 7), with a 7-day interval between visits (interval of 5 to 56 days is allowed).
- Group 2: 2²ID regimen (N = 187): received PrEP at least 5 years ago through 2 x 0,1 mL ID injections (Day 0 and Day 7) with a 7-day interval between visits (interval of 5 to 56 days is allowed).
- Group 3: 1²ID regimen (N = 187): received PrEP at least 5 years ago through 2 x 0,1 mL ID injections on Day 0
All subjects will receive 1 x 1,0 mL IM injection of purified chick-embryo cell-culture rabies vaccine as sPEP (booster) at least five years after primary vaccination (PrEP).
Neutralizing antibody titers against rabies virus will be measured using the Rapid Fluorescent Focus Inhibition Test (RFFIT) on Day 0 (before administration of sPEP) and on Days 7 and 14 after sPEP vaccination.
A titre of ≥ 0.5 IU/mL is defined as adequate (WHO standard).
Study design
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Group 1: 2 x 1IM regimen, (N = 187): | Experimental | Biological: Booster vaccinationHealthy volunteers that received Pre-Exposure Prohphylaxis (PrEP) (a rabies vaccination) at least 5 years ago through 1 x 1,0 mL IM injection (Day 0 and Day 7), with a 7-day interval between visits (interval of 5 to 56 days is allowed). |
| Group 2: 2²ID regimen (N = 187): | Experimental | Biological: Booster vaccinationReceived PrEP vaccination (Pre-Exposure prophylaxis usinga rabies vaccine) at least 5 years ago through 2 x 0,1 mL ID injections (Day 0 and Day 7) with a 7-day interval between visits (interval of 5 to 56 days is allowed). |
| Group 3: 1²ID regimen (N = 187) | Experimental | Biological: Booster vaccinationreceived PrEP (Pre-Exposure prophylaxis using a rabies vaccine) at least 5 years ago through 2 x 0,1 mL ID injections on Day 0 |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- ≥ 18 to ≤ 60 years of age at time of inclusion
- Willingness to provide written informed consent
- Having received PrEP with a 21IM, 2²ID or 1²ID regimen at least 5 years before starting the study. For 21IM and 2²ID interval of 5 days to 56 days between the 2 visits is allowed.
Key exclusion criteria (8 listed)
- Known allergy to one of the components of the vaccine.
- Subjects, who received immunomodulating therapy within the last 3 months (12 weeks).
- Note: See Section 6.3 for detailed guidance on immunomodulating therapies.
- Planned vaccination with any inactivated vaccine within 2 weeks before or after vaccination in the study or with any live attenuated vaccine within 1 month before or after each vaccination in the study.
- Ongoing pregnancy or active child wish at the time of booster vaccination (D0).
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 |
|---|---|---|
| Booster vaccinationTo investigate whether the boostability of a (A) two-visit IM, (B) two-visit ID and (C) one-visit ID pre-exposure vaccination regimen is non-inferior to a theoretical 99% boostability by administering a single-dose IM booster to simulate exposure to rabies at least 5 years after the pre-exposure regimens regimen. | Biological | Group 1: 2 x 1IM regimen, (N = 187):, Group 2: 2²ID regimen (N = 187):, Group 3: 1²ID regimen (N = 187) |
Primary outcome
Primary: boostability
Time frame: 13 months - from First Patient In (FPI) to Last Patient Out (LPO)
To investigate whether the boostability of a (A) two-visit IM, (B) two-visit ID and (C) one-visit ID Pre-exposure Prophylaxis (PrEP) regimen is non-inferior to a theoretical 99% boostability when a single-dose IM simulated Post Exposure Prophylaxis (sPEP) is administered at least 5 years after the PrEP regimen. Primary Endpoint: Proportion of participants that have an adequate immune response (Rapid Fluorescent Focus Inhibition Test (RFFIT) level, WHO standard) on Day 7 after the booster.
7 secondary outcomes
RFFIT levels ≥ 0.5 IU/mL Day 14
Time frame: 14 days following booster vaccination
FFIT levels ≥ 0.5 IU/mL on the day of the booster (Day 0).
Time frame: Day 0 - on day of booster vaccination
RFFIT levels ≥ 3.0 IU/mL on Day 7 after the booster
Time frame: Day 7 - following booster vaccination
RFFIT levels ≥ 3.0 IU/mL on Day 14 after the booster.
Time frame: Day 14 after the booster vaccination
RFFIT levels ≥ 10 IU/mL on Day 7 after the booster.
Time frame: Day 14 following the booster vaccination
RFFIT levels ≥ 10 IU/mL on Day 14 after the booster.
Time frame: Day 14 following the booster vaccination.
Safety objectives
Time frame: 1. & 2. Day 7 following the booster vaccination. 3. 13 months - entire study duration FPI to LPO
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Mar 2026.
- Individual participant dataSharing planned: No
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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.
Clinical Trial Unit Clinical Trial Unit Insitute of Tropical Medicine Antwerp, MsC contact
6 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Booster vaccination in people with Rabies (Healthy Volunteers), run by Institute of Tropical Medicine, Belgium at 6 sites in Belgium.
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 3 inclusion and 8 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: opening soon, as of the sponsor's last update on 6 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 6 sites in Belgium. 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 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
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 Thomas Hendrickx, MsC (000000000000000000000000000000, thendrickx@itg.be), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Primary: boostability (time frame: 13 months - from First Patient In (FPI) to Last Patient Out (LPO)). 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 6 Mar 2026.