A Phase 1 interventional study of Prime-2-CoV_Beta in COVID-19, sponsored by University Hospital Tuebingen. Active, not recruiting at 2 sites in Germany. Open to participants aged 18 Years to 55 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-06-15.
Sponsored by University Hospital Tuebingen · Phase 1, Interventional, and Prevention
This is an open-label, first-in-human, dose-finding study to evaluate the safety and immunogenicity of a booster vaccination of Prime-2-CoV_Beta in healthy participants.
Eligible participants will undergo baseline assessments and will receive 1 injection of Prime-2-CoV_Beta at Day 1. Participants will be followed up through 6 months post-booster vaccination. Follow-up visits will be performed at Days 4, 8, 15, 29, and Months 3 and 6, to assess the safety, tolerability, and immunogenicity of Prime-2-CoV_Beta. Additional safety and tolerability data will be assessed 1 day and 2 days after booster vaccination (Days 2 and 3) by telephone. Initially, a total of 60 participants were planned to be vaccinated in 5 cohorts of 12 participants each. Dose ranging of Prime-2-CoV_Beta was planned to be done by dose escalation with doses ranging from 3x104 plaque forming units (PFUs) up to 3x10\^7 PFUs.
With protocol Version 7.0, Cohort 6 with 12 participants was added with 6x10\^7 PFU. With protocol Version 8.0, 1 additional cohort, Cohort 7 (1.2x10\^8 PFU, stratified by previous COVID-19 vaccinations and previous SARS-CoV-2 infections) with 24 participants will be added (total number thus 96 participants).
Procedures for Cohorts 6 and 7 will be the same as for Cohorts 1 - 5, except that for some participants in Cohort 7 ORFV shedding in urine, saliva, blood, and stool will be evaluated.
7,640 studies on the registry are indexed under COVID-19; 488 are open to participants now.
This study's planned enrollment of 96 is close to the median of 100 across 4,099 interventional studies indexed under COVID-19.
Browse COVID-19 studies →University Hospital Tuebingen is the lead sponsor of 476 studies on the registry; 104 are open to participants now.
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Inclusion Criteria:
Inclusion criteria
Previous COVID-19 vaccination and previous SARS-CoV-2 infection as follows:
Women of childbearing potential must:
A highly effective method of contraception or birth control (failure rate less than 1% per year when used consistently and correctly) for this study: combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, transdermal, injectable), progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, implantable), intrauterine device, intrauterine hormone-releasing system, bilateral tubal occlusion, sexual abstinence or vasectomized sexual partner. Abstinence is only acceptable as true abstinence when this is in line with the preferred and usual lifestyle of the participant (abstinent on a long-term and persistent basis). The reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical study and the preferred and usual lifestyle of the participant. (Periodic abstinence [e.g., calendar, ovulation, symptothermal, post-ovulation methods and withdrawal] are not acceptable methods of contraception.) Postmenopausal (no menses for at least 1 year without alternative medical cause) or surgically sterile women (tubal ligation, hysterectomy or bilateral oophorectomy) may be enrolled.
Male participants must agree not to intend to father a child or to donate sperm starting at Screening, throughout the clinical study. Male participants must also
Exclusion Criteria:
Previous and concomitant therapy:
Chronic administration of medication associated with impaired immune responsiveness as judged by the investigator (including, but not limited to: immunosuppressive therapy, systemic corticosteroids exceeding 10 mg/day of prednisone equivalent, allergy shots for hypo-sensitization, immunoglobulin, interferon, immunomodulators, cytotoxic drugs, or other similar or toxic drugs) within 2 months before the Prime-2-CoV_Beta booster vaccination (Day 1). Inhaled/nebulized, intra-articular, intrabursal, or topical (skin or eyes) corticosteroids are permitted.
Previous and concomitant medical condition:
Current or history of alcohol and/or drug abuse within the last 6 months before Day 1
Previous and concomitant clinical study experience
Current participation in another study or previous enrollment in this clinical study
Other exclusion criteria
Prime-2-CoV\_Beta, dose: 30 000 PFUs
Biological: Prime-2-CoV_Beta
Prime-2-CoV\_Beta, dose: 300 000 PFUs
Biological: Prime-2-CoV_Beta
Prime-2-CoV\_Beta, dose: 3 000 000 PFUs
Biological: Prime-2-CoV_Beta
Prime-2-CoV\_Beta, dose: 150 000 000 PFUs
Biological: Prime-2-CoV_Beta
Prime-2-CoV\_Beta, dose: 30 000 000 PFUs
Biological: Prime-2-CoV_Beta
Prime-2-CoV\_Beta, dose: 60 000 000 PFUs
Biological: Prime-2-CoV_Beta
Prime-2-CoV\_Beta, dose: 1 200 000 000 PFUs
Biological: Prime-2-CoV_Beta
1 intramuscular injection (1.0 mL each) into the deltoid muscle on Day 1
Proportion of participants with treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) throughout the study
All safety data will be summarized descriptively overall and by cohort. TEAEs will be summarized by descriptive statistics using contingency tables (counts of events, number and proportion of participants with events) and presented by system organ class and preferred term, as well as by severity.
Time frame: Day 1 (vaccination day) to month 6 (end of study visit, ±14 days)
Proportion of participants with solicited local adverse events (first 7 days after Prime-2-CoV_Beta booster vaccination): pain at injection site, redness, induration, and swelling.
Solicited local adverse events will be summarized by descriptive statistics using contingency tables (counts of events, number and proportion of participants with events).
Time frame: Day 1 (vaccination day) to day 8 (Visit 3; ±1 day)
Proportion of participants with solicited systemic adverse events (first 7 days after Prime-2-CoV_Beta booster vaccination): fever, fatigue, headache, chills, vomiting, nausea, diarrhea, new or worsened muscle pain, new or worsened joint pain.
Solicited systemic adverse events will be summarized by descriptive statistics using contingency tables (counts of events, number and proportion of participants with events).
Time frame: Day 1 (vaccination day) to day 8 (Visit 3; ±1 day)
Proportion of participants with unsolicited treatment-emergent adverse events throughout the study
All unsolicited adverse events which occur after the first administration of investigational product are defined as treatment-emergent adverse events. Treatment-emergent adverse events will be summarized by descriptive statistics using contingency tables (counts of events, number and proportion of participants with events) and presented by system organ class and preferred term, as well as by severity.
Time frame: Day 1 (vaccination day) to month 6 (end of study visit, ±14 days)
Level of neutralizing antibody titers versus SARS CoV-2 (Wuhan wild type) at each post-booster vaccination assessment
Immunogenicity endpoints will be descriptively analyzed by cohort and visit. Separate analyses will be done for the different parameters, e.g., different antibodies evaluated with different serological immunogenicity assays.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean fold rise (GMFR) of neutralizing antibodies (versus Wuhan wild type) from Baseline to each post-booster vaccination assessment
The fold change from Baseline will be computed for each participant. The fold rise is calculated as the ratio of the post- vs pre-vaccination titer value. The fold change from Baseline will be summarized using descriptive statistics by cohort and visit. Additionally, the GMFR with 95% CI will be presented.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
IgG antibody titer versus SARS-CoV-2 receptor-binding protein
Immunogenicity endpoints will be descriptively analyzed by cohort and visit. Separate analyses will be done for the different parameters, e.g., different antibodies evaluated with different serological immunogenicity assays.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean titers (GMT) of receptor-binding protein-specific IgG antibodies
Immunogenicity endpoints will be descriptively analyzed by cohort and visit. Separate analyses will be done for the different parameters, e.g., different antibodies evaluated with different serological immunogenicity assays.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean fold rise of receptor-binding protein-specific IgG antibodies from Baseline
The fold change from Baseline will be computed for each participant. The fold rise is calculated as the ratio of the post- vs pre-vaccination titer value. The fold change from Baseline will be summarized using descriptive statistics by cohort and visit. Additionally, the geometric mean fold rise with 95% confidence interval will be presented.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Proportion of participants with adverse events of special interest throughout the study
Adverse events of special interest will be summarized by descriptive statistics using contingency tables (counts of events,number and proportion of participants with events) and presented by system organ class and preferred term, as well as by severity. The frequency (% of participants) of adverse events of special interest throughout the study will be tabulated.
Time frame: Day 1 (vaccination day) to day 8 (Visit 3; ±1 day)
IgG antibody titer versus SARS-CoV-2 S1 protein
Immunogenicity endpoints will be descriptively analyzed by cohort and visit. Separate analyses will be done for the different parameters, e.g., different antibodies evaluated with different serological immunogenicity assays.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean titers of IgG S1-specific antibodies
Absolute values of serological immunogenicity assays as described will be presented using descriptive summary statistics by cohort and visit. Additionally, Geometric mean titers with 95% confidence interval (CI) will be provided. For each cohort, serological immunogenicity assays will be presented graphically displaying Geometric mean titers with 95% CIs at all visits.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean fold rise of IgG S1-specific antibodies from Baseline
The fold change from Baseline will be computed for each participant. The fold rise is calculated as the ratio of the post- vs pre-vaccination titer value. The fold change from Baseline will be summarized using descriptive statistics by cohort and visit. Additionally, the geometric mean fold rise with 95% CI will be presented.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
IgG antibody titer versus SARS-CoV-2 N-protein
Immunogenicity endpoints will be descriptively analyzed by cohort and visit. Separate analyses will be done for the different parameters, e.g., different antibodies evaluated with different serological immunogenicity assays.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean titers of N-specific IgG antibodies
Absolute values of serological immunogenicity assays as described will be presented using descriptive summary statistics by cohort and visit. Additionally, geometric mean titers with 95% confidence interval (CI) will be provided. For each cohort, serological immunogenicity assays will be presented graphically displaying geometric mean titers with 95% CIs at all visits.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean fold rise of N-specific IgG antibodies from Baseline
The fold change from Baseline will be computed for each participant. The fold rise is calculated as the ratio of the post- vs pre-vaccination titer value. The fold change from Baseline will be summarized using descriptive statistics by cohort and visit. Additionally, the geometric mean fold rise with 95% confidence intervals will be presented.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Level of neutralizing antibody titers versus the variant of concern SARS-CoV-2_Beta, SARS-CoV-2_Delta and SARS-CoV-2_Omicron at each post-booster vaccination assessment
Immunogenicity endpoints will be descriptively analyzed by cohort and visit. Separate analyses will be done for the different parameters, e.g., different antibodies evaluated with different serological immunogenicity assays.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Geometric mean fold rise of neutralizing antibodies from Baseline to each post-booster vaccination assessment
The fold change from Baseline will be computed for each participant. The fold rise is calculated as the ratio of the post- vs pre-vaccination titer value. The fold change from Baseline will be summarized using descriptive statistics by cohort and visit. Additionally, the geometric mean fold rise with 95% confidence intervals will be presented.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 3 (±14 days), month 6 (end of study visit, ±14 days)
Percentage of cytokine producing S and N protein-specific T-cells compared to Baseline
Analyses based on S- and N-specific antibodies will be performed as described for receptor-binding protein specific antibodies.
Time frame: Day 1 (vaccination day), day 8 (±1 day), day 15 (±2 days), day 29 (±1 day), month 6 (end of study visit, ±14 days)
Additional assays to measure the immune response to Prime-2-CoV_Beta and the immune response to the Orf virus vector backbone
Orf virus-specific antibodies will be summarized descriptively as described for virus-specific antibodies.
Time frame: Day 1 (vaccination day), day 15 (±2 days), day 29 (±1 day), month 6 (end of study visit, ±14 days)
Additional assays to measure ORF virus (ORFV) shedding in urine, saliva, blood, and stool
ORFV shedding will be assessed with quantitative polymerase chain reaction to allow detection of genome copies of ORFV.
Time frame: Day 1 (vaccination day), day 2, day 4, day 8 (±1 day)
Plan to share: No
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University Hospital Tuebingen