A Phase 2 interventional study of Booster dose of the recombinant zoster vaccine (RZV, Shingrix®) in Zoster; Herpes, sponsored by Oriol Manuel. Not yet recruiting at 1 site in Switzerland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-03-02.
Sponsored by Oriol Manuel · Phase 2, Interventional, and Prevention
Shingles is caused by the same virus that causes chickenpox. After someone has chickenpox, the virus stays in the body and can become active again later in life. This is called shingles.
People who have received a solid organ transplant (such as a kidney, liver, or heart transplant) are 3 to 10 times more likely to get shingles than the general population. In transplant patients, shingles is often more severe. It can spread to other parts of the body and may cause long-lasting nerve pain. These problems can lower quality of life, increase doctor visits and hospital care, and may even affect how well the transplanted organ works.
The shingles vaccine called Shingrix® (recombinant zoster vaccine, RZV) works well in healthy adults and is generally safe for transplant patients. However, about 30% of transplant recipients still develop shingles even after receiving the recommended two doses. This may be because their immune system is weakened by the long-term medicines they take to prevent organ rejection.
The purpose of this clinical trial is to find out whether giving an extra (booster) dose of the shingles vaccine after transplant can improve the immune response in solid organ transplant recipients.
This study aims to answer the following questions:
Participants in the study will:
Herpes zoster (named zoster thereafter) results from reactivation of latent varicella-zoster virus (VZV) and represents a major cause of morbidity in immunocompromised populations. Among SOT recipients, the incidence of zoster is estimated to be 3-10 times higher than in the general population. In these patients, zoster is often more severe and associated with disseminated disease, and a higher risk of post-herpetic neuralgia. These complications may not only impair quality of life but also increase healthcare utilization and risk of graft dysfunction.
The recombinant zoster vaccine (RZV, Shingrix®) has shown high efficacy in immunocompetent adults. In immunocompromised populations, RZV demonstrated safety and moderate immunogenicity, including in patients who received autologous stem cell transplantation and renal transplantation. However, breakthrough infections remain frequent, affecting approximately 30% of immunocompromised patients despite prior vaccination.
The immunological mechanisms underlying these breakthrough cases likely include waning immunity and the effects of chronic immunosuppressive therapy. Since transplant recipients must receive long-term immunosuppressive drugs to prevent graft rejection, their immune system is less capable of maintaining effective vaccine-induced immunity. We hypothesize that administering an additional booster dose of RZV after transplantation could restore or enhance immune responses, leading to improved protection against zoster.
To date, no systematic clinical trial has evaluated this booster approach in solid-organ transplantation. The ZEST pilot trial therefore addresses an important evidence gap, with the potential to establish a novel vaccination strategy for this high-risk population. The trial will generate key immunological data to inform the feasibility, safety, and biological plausibility of post-transplant booster vaccination, laying the groundwork for a future multicentre randomized trial with clinical endpoints such as incidence of zoster.
SOT recipients will be identified through the transplantation center and approached during routine follow-up visits, or via mailed invitations. After receiving study information and providing written or electronic consent, participants will be randomized in a 2:1 ratio to receive a booster dose of RZV or no intervention. Randomisation and vaccination will take place either during a routine outpatient visit or in a dedicated vaccination unit to minimize additional workload for clinical staff. Blood samples will be collected at four predefined time points: at the time of vaccination (baseline) and at 1, 6, and 12 months after the booster dose. An additional blood sample at the time of transplantation may be obtained via the STCS biobank if available.
Participants randomized to the intervention arm will receive a single intramuscular injection of Shingrix® (0.5 mL recombinant glycoprotein E antigen with AS01B adjuvant) administered into the deltoid muscle. The booster will be administered at least 6 months after transplantation. Vaccine supply, storage (2-8°C), and accountability will be managed by the hospital pharmacy according to GCP standards.
The control group will not receive any intervention
180 studies on the registry are indexed under Chickenpox; 28 are open to participants now.
This study's planned enrollment of 75 is below the median of 475 across 149 interventional studies indexed under Chickenpox.
Browse Chickenpox studies →Oriol Manuel is the lead sponsor of 3 studies on the registry; 2 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Control participants will not receive an injection but will undergo blood sampling at the same time points as the experimental group - baseline (pre-randomization), and at 1, 6 and 12 months - to ensure comparability of immunological data. They will continue standard post-transplant care and routine clinical follow-up according to institutional practice.
The intervention group will receive a RZV booster dose. Vaccine reconstitution will follow the manufacturer's instructions immediately before injection. Administration will be performed by a trained study nurse or investigator under medical supervision. Participants will be observed for at least 15 minutes post-injection to detect any immediate hypersensitivity or vasovagal reaction. No deviation from the commercial formulation or packaging is expected. The IMP used in this trial is identical to the marketed product authorized in Switzerland and the EU.
Biological: Booster dose of the recombinant zoster vaccine (RZV, Shingrix®)
Participants randomized to the intervention arm will receive a single intramuscular injection of Shingrix® (0.5 mL recombinant glycoprotein E antigen with AS01B adjuvant) administered into the deltoid muscle. The booster will be administered at least 6 months after transplantation. Vaccine supply, storage (2-8°C), and accountability will be managed by the hospital pharmacy according to GCP standards.
Proportion of participants with ≥2-fold increase in anti-gE antibody titers from baseline
The primary outcome of this study is the humoral immune response 4 weeks after the booster dose of RZV. This will be defined as the proportion of participants achieving at least a two-fold increase in anti-gE antibody titers compared with baseline levels, measured by anti-gE ELISA.
Time frame: 4 weeks after booster dose
Frequency of VZV-specific CD4+ T-cells, (as % of total CD4+ T-cells)
Magnitude and frequency of VZV-specific CD4+ T-cell responses at 1, 6, and 12 months post-vaccination, measured by flow cytometry
Time frame: 4 weeks, 6 months and 12 months after booster dose
Geometric mean anti-gE antibody titers
Geometric mean titers (GMT) at 6 and 12 months post-vaccination, including pre- and post-transplantation changes.
Time frame: 6 and 12 months after booster dose
Incidence of confirmed herpes zoster cases
Clinically diagnosed zoster cases, preferably PCR-confirmed, via medical record review.
Time frame: Through study completion, an average of 1 year
Number of participants with vaccine-related treatment-emergent adverse events, graded according to CTCAE v4.0
Local and systemic solicited adverse events following vaccination, documented in medical records and graded according to CTCAE v4.0 where applicable.
Time frame: From baseline to 4 weeks after the booster dose.
Number of participants with serious adverse events and episodes of graft rejection, graded according to CTCAE v4.0 where applicable
Serious adverse events and episodes of graft rejection, documented in medical records and graded according to CTCAE v4.0 where applicable.
Time frame: Through study completion, an average of 1 year
Plan to share: Yes — After the study is completed, de-identified individual participant data may be shared. Data will be made available only after a formal request to the Principal Investigator (PI) and approval by the study's Scientific Committee. Data sharing will be limited to use for scientific research purposes and will follow all applicable privacy and ethical regulations.
Supporting information: Study protocol, Statistical analysis plan, Clinical study report
Start is estimated for Apr 2026; primary completion for Dec 2026, 8 months later.
Of 17 phase 2 interventional studies under Chickenpox, half reached primary completion within 17 months of starting (the median), counting those still running; a quarter within 7 and three quarters within 38. This study's planned 8 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Feb 2026. You cannot join it, but the record below documents what was studied.
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