A Phase 1/2 interventional study of Test Drug 1-1 (GBP511 low dose) and Test Drug 1-2 (GBP511 mid dose) in Healthy Participants and Sarbecovirus, sponsored by SK Bioscience Co., Ltd.. Active, not recruiting at 3 sites in Australia. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-09.
Sponsored by SK Bioscience Co., Ltd. (part of SK Chemicals Co., Ltd.) · Phase 1/2, Interventional, and Prevention
The purpose of this research study is to evaluate the safety of and the body's immune response to single and multiple vaccinations in healthy men and women. We want to find out what effects GBP511 has on you and your health. We are doing this study to find out:
If the study drug has any side effects when given as single and multiple vaccinations.
If reactogenicity, an indication that the immune systems is working and is preparing to protect the body against future infection, occurs. This is a normal physical inflammatory response that occurs after vaccination, manifesting as localised reactions that may include pain or redness at the injection site, or systemic symptoms such as headache or fever.
If immunogenicity which is when GBP511 causes your body to make antibodies against the non-harmful viral proteins contained within GBP511, called 'neutralising antibodies (Nab),' occurs. And if GBP511 will cause the specialised cells of the body's immune system to mount a defence against the non-harmful viral proteins contained within GBP511, called 'cell-mediated immunity (CMI)'.
In this study, GBP511 will be administered with and without adjuvant, CAS-1. An adjuvant is an ingredient used in some vaccines that help produce a stronger immune response in the people receiving the vaccine and thus helps the vaccine work better.
This study will recruit approximately 368 participants in total and will be conducted in two stages:
Stage 1 will look at two vaccinations with GBP511 when given with and without the CAS-1 adjuvant; and Stage 2 will look at either one or two vaccinations with two candidate GBP511 vaccines chosen from Stage 1 of the study.
Participants will be required to attend Linear's clinical unit on two separate occasions to receive their two vaccinations. On the first day of dosing (Visit 2/Day 1) and second day of dosing (Visit 5/Day 29), we will be testing a single dose of the study drug in up to 168 healthy volunteers who will be divided into 3 groups. Group 1, Groups 2 and 3 will have 56 people each. These 3 groups will be divided into treatment subgroups, with a total of 6 test subgroups and 3 control subgroups. In all groups, neither you or the study doctor will know what subgroup you are part of, and therefore what treatment (GBP511 or Comirnaty+ placebo) you will receive.
SK Bioscience Co., Ltd. is the lead sponsor of 12 studies on the registry; 1 is open to participants now.
Counted across the registry records on this site, refreshed daily.
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.
Age
For Stage 1, participant must be 18 to 55 years of age inclusive, at the time of signing the .
For Stage 2, participant must be 18 years of age and older, at the time of signing the informed consent.
Type of Participant and Disease Characteristics
Participants who received a primary series and at least one booster dose of an authorized COVID-19 vaccine at least 24 weeks prior to the 1st study vaccination.
Sex and /Barrier Requirements
Women of (WOCBP) with a negative urine or serum pregnancy test at screening.
* Female participants who are surgically sterile (e.g., having undergone a full hysterectomy, bilateral salpingectomy, or bilateral oophorectomy) or with at least 12 months amenorrhoea not considered to be caused by any other medical condition, are not subject to a pregnancy test.
Informed Consent
Exclusion Criteria:
Medical Conditions
Female participants who are pregnant or breastfeeding.
Prior/Concomitant therapy
Receipt of therapy, such as any use of anti-cancer chemotherapy or radiation therapy; or chronic use of systemic (≥10 mg prednisone/day or equivalent more than 14 consecutive days) within 12 weeks prior to the 1st study vaccination and throughout the entire study period. The use of intranasal, inhaled, topical, or intra-articular corticosteroid is permitted.
Prior/Concurrent Clinical Study Experience
Participation in another clinical study and receipt of study intervention within 4 weeks prior to the 1st study vaccination, or concurrent, planned participation in another clinical study with study intervention during this study period.
Other Exclusions
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Low-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (2µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5)
Biological: Test Drug 1-1 (GBP511 low dose)
Low-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (2µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5)
Biological: Test Drug 2-1 (GBP511 low dose + CAS-1)
Comirnaty (2025-26 or subsequent seasonal formulation, 30 mcg of SARS-CoV-2 LP.8.1 spike protein mRNA); a total injection volume of 0.3mL Normal saline; a total injection volume of 0.5mL Comirnaty: IM injection on Day 1 (Visit 2) Normal Saline: IM injection on Day 29 (Visit 5)
Biological: Comparator (Comirnaty) · Biological: Placebo (Normal Saline)
Mid-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (6µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5)
Biological: Test Drug 1-2 (GBP511 mid dose)
Mid-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (6µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5)
Biological: Test Drug 2-2 (GBP511 mid dose + CAS-1)
High-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (18µg of RBD/strain); a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5)
Biological: Test Drug 1-3 (GBP511 high dose)
High-dose of recombinant protein nanoparticle pan-Sarbecovirus vaccine (18µg of RBD/strain) adjuvanted with a standard dose of CAS-1; a total injection volume of 0.5mL IM injections on Day 1, 29 (Visit 2, 5)
Biological: Test Drug 2-3 (GBP511 high dose + CAS-1)
Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1.
Biological: Test Drug 13 (Stage 2, GBP511-A or B)
Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1.
Biological: Test Drug 14 (Stage 2, GBP511-A or B)
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose
injection volume of 0.5mililiter (mL) with 2-doses at 4 weeks interval in stage 1 and 1-dose or 2-doses at 4 weeks interval in stage 2. GBP511 - Low dose: 2μg/strain, Mid dose: 6μg/strain, High dose: 18μg/strain CAS-1 standard adjuvant dose
injection volume of 0.3mililiter (mL) with single-dose at visit 2. 30 mcg of SARS-CoV-2 LP.8.1 spike protein mRNA per 0.3mL
injection volume of 0.5mililiter (mL) with single-dose at visit 5.
Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1.
Participants will receive 2 intramuscular injections of the test vaccine in stage 2. Injections on Day 1, 29 (Visit 2, 5), in line with the selected dose regimen in stage 1.
Percentage of participants experiencing any immediate reactions
For stage 1
Time frame: 30 minutes (2 hours for sentinel participants) following each study vaccination
Percentage of participants reporting any solicited local AEs
For stage 1
Time frame: during the 7 days following each study vaccination
Percentage of participants reporting any solicited systemic AEs
For stage 1
Time frame: during the 7 days following each study vaccination
Percentage of participants experiencing any unsolicited AEs
For stage 1
Time frame: during the 28 days following each study vaccination
Percentage of participants experiencing any SAEs, MAAEs, AESIs, as well as AE leading to study withdrawal
For stage 1
Time frame: 1st Vaccination date, 1 week, 2 weeks, 4 weeks following the 1st study vaccination, and 2nd vaccination date, 1 week, 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
GMT of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay at each time point.
For stage 2
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
GMR of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
For stage 2
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Percentage of participants with ≥ 2-fold and 4-fold rises against each matched strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point
For stage 2
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Geometric mean titer (GMT) of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay
For stage 1
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
Geometric mean ratio (GMR) of neutralizing antibody against each matched strain measured by a pseudo-virus neutralization assay
For stage 1
Time frame: From pre-vaccination to baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
Percentage of participants with ≥ 2-fold and 4-fold rises against each matched strain in pseudo-virus neutralizing antibody titer
For stage 1
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination.
GMT of RBD-binding IgG antibody against each matched strain measured by ECL assay at each time point.
For stage 1,2
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2)
GMR of RBD-binding IgG antibody against each matched strain measured by ECL assay, from each pre-vaccination to subsequent time point.
For stage 1,2
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination(following the last vaccination for stage 2).
Percentage of participants with ≥ 2-fold and 4-fold rises in RBD-binding IgG titer against each matched strain, measured by ECL assay, from baseline to each subsequent time point.
For stage 1,2
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination(following the last vaccination for stage 2).
GMT of neutralizing antibody against each mismatched strain measured by a pseudo-virus neutralization assay at each time point.
For Stage 1, The endpoints will be evaluated exclusively in a subset of approximately 33% of participants at the following time points: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination. For Stage 2, The endpoints will be evaluated exclusively in a subset of approximately 20% of participants at the following time points: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Time frame: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
GMR of neutralizing antibody against each mismatched strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
For Stage 1, The endpoints will be evaluated exclusively in a subset of approximately 33% of participants at the following time points: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination. For Stage 2, The endpoints will be evaluated exclusively in a subset of approximately 20% of participants at the following time points: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Time frame: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
Percentage of participants with ≥ 2-fold and 4-fold rises against each mismatched strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point.
For Stage 1, The endpoints will be evaluated exclusively in a subset of approximately 33% of participants at the following time points: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination. For Stage 2, The endpoints will be evaluated exclusively in a subset of approximately 20% of participants at the following time points: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Time frame: baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the 2nd study vaccination (following the last vaccination for stage 2).
Cell-mediated response for both Th1 and Th2 cytokines (including but not limited to IFN-γ, IL-2, and IL-4 produced by T lymphocytes) measured by FluoroSpot
For Stage 1, The following endpoint will be evaluated exclusively in sentinel participants at the following time points: baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the 2nd study vaccination. For Stage 2, The following endpoints will be evaluated exclusively in a subset of approximately the first 20% of participants at the following time points: baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the last study vaccination.
Time frame: baseline, 2 weeks following the 1st study vaccination, and 2 weeks, and 6 months following the 2nd study vaccination(following the last vaccination for stage 2).
Percentage of participants experiencing any immediate reactions
For stage 2
Time frame: within 30 minutes following each study vaccination
Percentage of participants reporting any solicited local AEs
For stage 2
Time frame: during the 7 days following each study vaccination
Percentage of participants reporting any solicited systemic AEs
For stage 2
Time frame: during the 7 days following each study vaccination
Percentage of participants experiencing any unsolicited AEs
For stage 2
Time frame: during the 28 days following each study vaccination
Percentage of participants experiencing any SAEs, MAAEs, AESIs, as well as AE leading to study withdrawal
For stage 2
Time frame: during the entire study period
GMT of neutralizing antibody against each strain measured by a pseudo-virus neutralization assay at each time point.
For Stage 1\&2, some of the following endpoints may be evaluated in a subset of participants at all or partial time points.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
GMR of neutralizing antibody against each strain measured by a pseudo-virus neutralization assay, from each pre-vaccination to subsequent time point.
For Stage 1\&2, some of the following endpoints may be evaluated in a subset of participants at all or partial time points.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
Percentage of participants with ≥ 2-fold and 4-fold rises against each strain in pseudo-virus neutralizing antibody titer, from baseline to each subsequent time point.
For stage 1\& 2, Some of the following endpoints may be evaluated in a subset of participants at all or partial time points.
Time frame: At baseline, 2 weeks, 4 weeks following the 1st study vaccination, and 2 weeks, 4 weeks, 3 months, 6 months, and 12 months following the last study vaccination.
GMT ratios of neutralizing antibody against each matched and mismatched strain measured by a pseudo-virus neutralization assay
For Stage 2
Time frame: Vaccination date, 2 weeks, 4 weeks, 3 months, 6 months, 12 months following the vaccination date.
GMT ratios of RBD-binding IgG antibody against each matched strain measured by ECL
For Stage 2
Time frame: Vaccination date, 2 weeks, 4 weeks, 3 months, 6 months, 12 months following the vaccination date.
Further evaluation of the safety and/or immunogenicity of GBP511 candidates may also be conducted using samples collected from study participants to undertake a range of exploratory analyses.
For Stage 1\&2
Time frame: - Stage 1 and Stage 2: 1st vaccination date, 2 weeks, 2nd vaccination date, 2 week, 4 week, 3 months, 6 month, 12 month - Stage 2 only: Vaccination date, 2 week, 4 week, 3 month, 6 month, 12 month
Started Jan 2026 (actual). Primary completion is estimated for Dec 2026, 10 months after the start.
How these figures are worked out, and which studies are left out of them.
This study is active, not recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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