A Phase 2 interventional study of Amezosvatein Antigen High Dose Arm A and Amezosvatein Antigen Low Dose Arm B in Herpes Zoster and Shingles, sponsored by Curevo Inc. Active, not recruiting at 14 sites in United States. Open to participants aged 50 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-09-30.
Sponsored by Curevo Inc · Phase 2, Interventional, and Prevention
The purpose of this study is to assess the safety and immunogenicity of amezosvatein (CRV-101), an investigational vaccine compared to Shingrix® for the prevention of herpes zoster in adults aged 50 years and older
In the first part of the trial, participants will be randomized 1:1:1 to amezosvatein high antigen dose (Arm A), amezosvatein low antigen dose (B), or Shingrix (C). In the second part of the trial, participants will be randomized 5:1 to receive amezosvatein adjuvant dose D or Shingrix (E), adjuvant dose F or Shingrix (G), or adjuvant dose H or Shingrix (I). In the third part of the trial, participants will be randomized 3:1 to receive amezosvatein adjuvant dose J or Shingrix (K) or amezosvatein adjuvant dose L or Shingrix (M). Both study vaccines, amezosvatein and Shingrix, will be administered by intramuscular injection on Month 0 and Month 2. Safety, reactogenicity, and immunogenicity analysis will be performed overall and by age group. Participants will be followed for safety, immunogenicity, and herpes zoster cases from Day 0 to the main study end (Month 14), and through the long-term follow up (LTFU) extension period of up to 5 additional years.
299 studies on the registry are indexed under Herpes Zoster; 55 are open to participants now.
This study's enrollment of 1,516 is above the median of 160 across 247 interventional studies indexed under Herpes Zoster.
Browse Herpes Zoster studies →Curevo Inc is the lead sponsor of 2 studies on the registry; none are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Participants are eligible to be included in the study only if all of the following criteria apply:
Male and non-pregnant female participant must be ≥50 years of age inclusive, at the time of signing the .
Participants who are healthy as determined by medical evaluation including comprehensive medical history, comprehensive physical examination, vital signs*, and screening laboratory tests conducted no more than 30 days prior to first study injection administration (Day 0).
Normal urinalysis or, if abnormal, urinalysis determined to be not clinically significant by the PI at screening.**
A female participant is eligible to participate if she is not pregnant or breastfeeding, and one of the following conditions applies:
WONCBP is as defined as
WOCBP is defined as
Exclusion Criteria
Participants are excluded from the study if any of the following criteria apply:
Abnormal blood pressure >150 mm Hg systolic or >95 mm Hg diastolic prior to first study injection administration (Day 0).***
*** If abnormal, BP may be repeated up to 3 times after a rest period of 5 minutes between each measurement.
Acute disease and/or fever at the time of enrollment (Day 0).
(a) Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs (e.g., oral or injected , such as prednisone; high-dose inhaled steroids; biologics (e.g., tumor necrosis factor [TNF] inhibitor, or other cytokine inhibitors within 14 days of Day 0 through Day 84, and within 14 days of each on study immunogenicity blood draw after Day 84; Exclusionary corticosteroid administration is defined as prednisone >20 mg/day (or equivalent) for any frequency; low-dose inhaled and topical and ocular steroids are allowed; (b) or cytotoxic therapies, such as chemotherapy drugs or radiation, from 180 days prior to enrollment, during the study through Day 421.
Participants who meet this criterion from 14a and 14b after Day 56, should continue to be followed for safety and immunogenicity but will not be in included in the per protocol population from the date of meeting the criterion.
Participation in another experimental protocol which includes the receipt of any investigational products/vaccines or devices within 90 days prior to enrollment (Day 0) in this study, or planned participation in another experimental protocol which includes investigational product/vaccine or device receipt during the study period through D421*. After the D421 visit, participation in another clinical study and with concurrent receipt of another experimental investigational product/vaccine or device is allowed with medical monitor approval. Any other investigational product/vaccine with immune modulating effect which would complicate the assessment of humoral and cellular responses, including investigational vaccines, must not be used 60 days prior to each LTFU extension year visit. Receipt of another experimental VZV vaccine or HSV vaccine is prohibited on the study.
*Prior to Day 421, concurrent participation in a study which previously included investigational product/vaccine receipt but is no longer receiving investigational products/vaccine, such as in an observational phase of the other study, is allowed.
[protocol v8.0]
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.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
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.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Autoimmune disease
A condition in which the immune system attacks the body’s own tissues, such as rheumatoid arthritis, lupus, psoriasis, type 1 diabetes or inflammatory bowel disease.
Immunotherapy studies often leave out active autoimmune disease, and some name exceptions, such as thyroid disease on replacement hormone. Check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational Vaccine
Biological: Amezosvatein Antigen High Dose Arm A
Investigational Vaccine
Biological: Amezosvatein Antigen Low Dose Arm B
Active comparator
Biological: Shingrix
Investigational Vaccine
Biological: Amezosvatein Adjuvant Dose Arm D
Active Comparator
Biological: Shingrix
Investigational Vaccine
Biological: Amezosvatein Adjuvant Dose Arm F
Active Comparator
Biological: Shingrix
Investigational Vaccine
Biological: Amezosvatein Adjuvant Dose Arm H
Active Comparator
Biological: Shingrix
Investigational Vaccine
Biological: Amezosvatein Adjuvant Dose Arm J
Active Comparator
Biological: Shingrix
Investigational Vaccine
Biological: Amezosvatein Adjuvant Dose Arm L
Active Comparator
Biological: Shingrix
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Suspension for injection administered intramuscularly (IM) in the deltoid region of the non-dominant arm in Month 0 and Month 2 per study schedule
Occurrence of solicited local and systemic signs and symptoms
Occurrence, severity, and duration of solicited local injection site reactions within 7 days (Day 0-Day 6) following each vaccination. (i.e., pain, redness, swelling) Occurrence, severity, and duration of solicited systemic reactions within 7 days (Day 0-Day 6) following each vaccination. (i.e., myalgia, fatigue, headache, chills, fever)
Time frame: Day 0-Day 6 for each vaccination timepoint
To compare the reactogenicity of amezosvatein to that of the standard 2-dose schedule of Shingrix®
Comparison of the proportion of participants reporting solicited local and systemic reactogenicity events following each vaccination
Time frame: Day 0-Day 6 for each vaccination timepoint
Occurrence of unsolicited non-serious adverse events
Occurrence, severity, and relationship to vaccination of unsolicited adverse events within 29 days (Day 0-Day 28) following each vaccination
Time frame: Day 0-Day 28 following each vaccination
Occurrence of serious adverse events (SAEs)
Occurrence and relationship to vaccination of all serious adverse events (SAE) from after first vaccination (Day 0) to main study end (Day 421 \[Month 14\])
Time frame: Day 0 - Day 421 [Month 14] (as noted in description)
Occurrence of adverse events (AEs) of special interest
Occurrence of any Potential Immune-Mediated Medical Conditions (PIMMCs) from post first vaccination (Day 0) to main study end (Day 421 \[Month 14\]) Medically attended adverse events (MAAEs) from post first vaccination (Day 0) to study end (Day 421 \[Month 14\])
Time frame: Day 0 - Day 421 [Month 14] (as noted in description)
To evaluate safety as measured by hematology and biochemistry parameters
Occurrence, intensity, and relationship to vaccination of clinically significant hematologic and biochemical adverse events at at Day 7 and Day 63
Time frame: Day 7 and Day 63
Vaccine protein-specific antibody concentrations (GMC) elicited by vaccination between Month 0 and Month 3
Assess humoral immune response as determined by Enzyme-linked Immunosorbent Assay (ELISA)
Time frame: Month 3
Vaccine Response Rate (≥ 4 fold increase in antibody concentration from pre-vaccination) at Month 3 for arms A, B, and C
• Assess humoral immune response as determined by Enzyme-linked Immunosorbent Assay (ELISA)
Time frame: Month 3
To compare the humoral immune response of Shingrix® to amezosvatein
Comparison of humoral response between amezosvatein and Shingrix at Month 3
Time frame: Month 3
Fold rise of vaccine protein-specific antibody concentrations elicited in response to vaccination for durability post Month 3
• Assess humoral immune response as determined by Enzyme-linked Immunosorbent Assay (ELISA)
Time frame: Month 3
Anti-Varicella Zoster Virus (VZV) neutralizing antibody titer in response to vaccination between Day 0 and Month 3 for arms A, B, and C
To assess the functional humoral immune response to vaccination (sub-study)
Time frame: Month 3
Frequency of vaccine protein-specific CD4+ T cells expressing at least 2 activation markers in response to vaccination between Month 0 and Month 3 for arms A, B, and C
To assess the cell-mediated immunity (CMI) immune response to vaccination as determined by intracellular cytokine staining (ICS)
Time frame: Month 3
To compare the frequency of vaccine protein-specific CD4+ T cells expressing at least 2 activation markers of Shingrix® to amezosvatein between Month 0 and Month 3 for arms A, B, and C.
To compare CMI immune response between amezosvatein and Shingrix® at Month 3
Time frame: Month 3
CMI Vaccine Response rate (≥ 2-fold increase in the frequency of vaccine protein-specific CD4+ T cell expressing at least 2 activation markers) at Month 3 for arms A, B, and C.
To assess the cell-mediated immunity (CMI) immune response to vaccination as determined by intracellular cytokine staining (ICS)
Time frame: Month 3
Vaccine Response Rate (≥ 4 fold increase in antibody concentration from pre-vaccination) at Month 3 for arms D through M
Assess humoral immune response as determined by Enzyme-linked Immunosorbent Assay (ELISA)
Time frame: Month 3
Vaccine protein-specific antibody concentrations elicited by response to vaccination for durability post Month 3
• Durability of humoral immunogenicity as determined by Enzyme-linked Immunosorbent Assay (ELISA)
Time frame: Month 14, and LTFU up to 5 additional years.
Fold rise of vaccine protein-specific antibody concentrations elicited in response to vaccination post Month 3
• Durability of humoral immunogenicity as determined by Enzyme-linked Immunosorbent Assay (ELISA)
Time frame: Month 14, and LTFU up to 5 additional years.
Frequency of vaccine protein-specific CD4+ T cells expressing at least 2 activation markers in response to vaccination for durability post Month 3
To assess the cell-mediated immunogenicity as determined by intracellular cytokine staining (ICS)
Time frame: Month 0, Month 14, and in LTFU up to 5 additional years.
To assess the correlation between vaccine protein-specific Ab concentrations, Anti-VZV neutralizing Ab titer, and frequency of vaccine protein-specific CD4+ T cells expressing >=2 activation markers for each vaccine and correlation across vaccines
The immunogenicity of amezosvtein alone or compared to Shingrix® will be further evaluated by methods to be determined. Exploratory analyses may include conducting analyses related to furthering the understanding of immunity to VZV and further characterization of the immune responses elicited by amezosvatein and/or in comparison to Shingrix
Time frame: Main study (Month 0 - Month 14) and LTFU up to 5 additional years.
To evaluate the incidence of clinically confirmed herpes zoster cases
Occurrence of clinically confirmed herpes zoster cases during the entire main study and LTFU extension period
Time frame: Main study (Month 0 - Month 14) and LTFU up to 5 additional years.
Frequency of vaccine protein-specific CD4+ T cells expressing at least 2 activation markers in response to vaccination between Month 0 and Month 3 for arms J, K, L, and/or M for dose selected for further development
To assess the cell-mediated immunity (CMI) immune response to vaccination as determined by intracellular cytokine staining (ICS)
Time frame: Month 3
To compare Shingrix® to amezosvatein on the frequency of vaccine protein-specific CD4+ T cells expressing at least 2 activation markers between Month 0 and Month 3 for arms J, K, L, and/or M for dose selected for further development
To compare CMI immune response between amezosvatein and Shingrix® at Month 3
Time frame: Month 3
CMI Vaccine Response rate (≥ 2-fold increase in the frequency of vaccine protein-specific CD4+ T cell expressing at least 2 activation markers) at Month 3 for arms J, K, L, and/or M for dose selected for further development
To assess the cell-mediated immunity (CMI) immune response to vaccination as determined by intracellular cytokine staining (ICS)
Time frame: Month 3
Occurrence of serious adverse events in long term follow up (LTFU) period
Occurrence of serious adverse events in long term follow up (LTFU) period
Time frame: LTFU period post Day 421 up to 5 additional years
Occurrence and relationship to vaccination of all serious adverse events (SAE) related or fatal in study participants in LTFU period
Occurrence and relationship to vaccination of all serious adverse events (SAE) related or fatal in study participants in LTFU period
Time frame: LTFU period post Day 421 up to 5 additional years
Occurrence of adverse events (AEs) of special interest
Occurrence of any Potential Immune-Mediated Medical Conditions (PIMMCs) in LTFU period
Time frame: LTFU period post Day 421 up to 5 additional years
Plan to share: No
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This study is active, not recruiting, as verified in Sep 2025. You cannot join it, but the record below documents what was studied.
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