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.

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Institute Of Tropical Medicine

Participant type

Healthy volunteers

Age range

18-64 years

Gender

Male and Female

Therapeutic area

Diseases [C] - Virus Diseases [C02]

Decision date (initial)

2026-05-19

Transition trial

No

Low-intervention

No

Rare-disease indication

No

Vulnerable population

Yes

Funding sources

Ministry of Defense (Belgian Armed Forces)

External identifiers

EU CT number

2025-524765-24-00

ClinicalTrials.gov

NCT07455318

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Prophylaxis, Efficacy

To investigate whether the boostability of a (A) two-visit Intra-muscular, (B) two-visit Intra-dermal and (C) one-visit Intradermal vaccination regimen is non-inferior to a theoretical 99% boostability when a single-dose Intramuscular vaccination is administered at least 5 years after the PrEP regimen.

Secondary objectives 10

1. Proportion of participant with adequate immune response (RFFIT levels ≥ 0.5 IU/mL) on Day 14 after the booster.
2. Proportion of participant with adequate immune response (RFFIT levels ≥ 0.5 IU/mL) on the day of the booster (Day 0)
3. Proportion of participants with good/robust protection (RFFIT levels ≥ 3.0 IU/mL) on Day 7 after the booster.
4. Proportion of participants with good/robust protection (RFFIT levels ≥ 3.0 IU/mL) on Day 14 after the booster.
5. Proportion of participants with long-lasting immunity (RFFIT levels ≥ 10 IU/mL) on Day 7 after the booster.
6. Proportion of participants with lonng-lasting immunity (RFFIT levels ≥ 10 IU/mL) on Day 14 after the booster.
7. Estimation of geometric mean titers (GMTs) per visit for the different arms and to compare the GMTs of subsequent visits to the baseline visit (day of the booster) per arm.
8. Proportion of solicited AEs (local reactions and general symptoms) occurring within 7 days after the sPEP vaccination session. (Day 7)
9. Proportion of unsolicited AEs occurring within 7 days after the sPEP vaccination session. (Day 7)
10. Proportion of Severe Adverse Events (SAE) occurring throughout the study period after sPEP vaccination session. (EOT)

Conditions and MedDRA coding

Rabies infection/prophylaxis

Study design 1 period

Regulatory references

Scientific advice from competent authorities

Institute Of Tropical Medicine

Plan to share IPD

No

IPD plan description

N/A - undecided

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 3

1. Age ≥ 18 and ≤ 60 years at the time of inclusion.
2. Willing and able to provide written informed consent.
3. Having received rabies Rabies vaccination through a 2x1 IM, 2²ID, or 1²ID regimen at least 5 years prior to study start.

Exclusion criteria 7

1. Subjects with a known allergy to one of the components of the vaccines
2. Currently receiving or having received immunomodulating drugs within the past 3 months (12 weeks).
3. Planned vaccination with any inactivated vaccine within 2 weeks before or after the vaccinations in the study or with any live attenuated vaccine within 1 month before or after the vaccinations in the study.
4. Ongoing pregnancy or active child wish (for female subjects) at the time of booster vaccination (D0).
5. Any other PrEP rabies vaccination schedules than those mentioned in the inclusion criteria.
6. Previous rabies booster vaccinations
7. Inability or unwillingness to comply with study procedures,

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 1

1. Proportion of participants that have an adequate immune response (Rapid Fluorescent Focus Inhibition Test (RFFIT) levels ≥ 0.5 IU/mL, WHO standard) on Day 7 after the booster.

Secondary endpoints 10

1. Proportion of participants with RFFIT levels ≥ 0.5 IU/mL on Day 14 after the booster.
2. Proportion of participants with RFFIT levels ≥ 0.5 IU/mL on the day of the booster (Day 0).
3. Proportion of participants with RFFIT levels ≥ 3.0 IU/mL on Day 7 after the booster
4. Proportion of participants with RFFIT levels ≥ 3.0 IU/mL on Day 14 after the booster.
5. Proportion of participants with RFFIT levels ≥ 10 IU/mL on Day 7 after the booster
6. Proportion of participants with RFFIT levels ≥ 10 IU/mL on Day 14 after the booster
7. geometric mean titers (GMTs) at all visits for all arms and the ratio with baseline GMTs per arm
8. Proportion of participants with swelling, pain, redness, headache, fever, or fatigue per arm.
9. Proportion of participants with unsolicited (i.e., other) Adverse events per arm. Proportion of participants with unsolicited local reactions per arm.
10. Proportion of participants with SAEs per arm throughout the study period after sPEP vaccination session. (EOT)

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 1

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Institute Of Tropical Medicine

Sponsor organisation

Institute Of Tropical Medicine

Address

Nationalestraat 155

City

Antwerp

Postcode

2000

Country

Belgium

Scientific contact point

Organisation

Institute Of Tropical Medicine

Contact name

Patrick Soentjens

Public contact point

Organisation

Institute Of Tropical Medicine

Contact name

Thomas Hendrickx - Clinical Trial Scientist

Locations

1 EU/EEA country · 6 investigational sites

By country

Investigational sites

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 35 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

1 submissions — initial application plus substantial / non-substantial modifications