Clinical Trial of Safety and Immunogenicity of Recombinant SARS-CoV-2 S-Trimer Vaccine (CHO Cells) as Booster Vaccination in Populations Aged 18 to 59 Years

Safety and Immunogenicity of a Recombinant SARS-CoV-2 S-Trimer Vaccine (CHO Cell) as Booster Shots in Healthy Adults Aged 18-59 Years Who Have Completed Two Doses of Inactivated SARS-CoV-2 Vaccine

Increased immune escape of emerging SARS-CoV-2 variants and waning neutralizing antibody levels over time indicate the importance of COVID-19 vaccine booster dose. Preclinical findings have shown that the recombinant SARS-CoV-2 S-Trimer vaccine exhibited favorable safety and immunogenicity. Herein, we conducted a randomized, open-label, positive control trial to assess the safety and immunogenicity of the booster shot in healthy subjects aged 18-59 years who have completed two-dose primary series of inactivated vaccine for 6-15 months. A total of 63 eligible participants were enrolled to receive the recombinant SARS-CoV-2 S-Trimer vaccine or inactivated vaccine, and only one participant in 30 μg recombinant SARS-CoV-2 S-Trimer vaccine cohort withdrew owing to personal work reasons on September 26, 2022. Subjects in each dose group (5 μg, 10 μg, 30 μg recombinant SARS-CoV-2 S-Trimer vaccine) was randomly assigned to receive the experimental vaccine or inactivated vaccine in a 2:1 ratio.

Study Overview

• Status: Terminated
• Conditions: COVID-19
• Intervention / Treatment: Biological: the recombinant SARS-CoV-2 S-Trimer vaccine/inactivated SARS-CoV-2 vaccine

• Study Type: Interventional
• Enrollment (Actual): 80
• Phase: Early Phase 1

Contacts and Locations

Study Locations

• China
  • Guangzhou
    • Guangzhou, Guangzhou, China, 510799
      • The Fifth Affiliated Hospital of Guangzhou Medical University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 59 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Eligible participants were those who completed the two-dose primary series of ICV for 6-15 months
• Voluntarily consented to participate in this trial
• Agreed to take effective contraceptive measures (women of childbearing potential) from signing the informed consent form to 12 months after booster vaccination.

Exclusion Criteria:

• History of allergy to any vaccine or its excipients;
• Presence of severe, uncontrollable or hospitalized diseases;
• History of major surgery within 3 months prior to enrollment;
• History of Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS) or COVID-19;
• Congenital or acquired immunodeficiency or autoimmune disease;
• Any acute diseases or acute attacks of chronic diseases within 7 days prior to enrollment;
• Receipt of any COVID-19 prophylactic medication other than primary series of ICV;
• Long-term receipt (>14 consecutive days) of glucocorticoids or other immunosuppressive agents within the past 6 months;
• Receipt of biological agents, immunopotentiators or immunosuppressants within the past 6 months;
• Receipt of blood or blood-related products within 3 months prior to vaccination;
• Administration of antipyretics, painkillers or antiallergics within 24 hours prior to vaccination;
• Participating or planning to participate in other clinical trials during the study period;
• Pregnant or lactating females, women of childbearing age of pregnancy test positive;
• Presence of any underlying disease or condition which, in the opinion of the investigator, may place the subject at unacceptable risk, is unable to meet the requirements of the protocol, or interfere with the assessment of vaccine response.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: the 5 μg recombinant SARS-CoV-2 S-Trimer vaccine booster group	Biological: the recombinant SARS-CoV-2 S-Trimer vaccine/inactivated SARS-CoV-2 vaccine; one booster dose intramuscularly in the deltoid muscle of the upper arm.
Experimental: the 10 μg recombinant SARS-CoV-2 S-Trimer vaccine booster group	Biological: the recombinant SARS-CoV-2 S-Trimer vaccine/inactivated SARS-CoV-2 vaccine; one booster dose intramuscularly in the deltoid muscle of the upper arm.
Experimental: the 30 μg recombinant SARS-CoV-2 S-Trimer vaccine booster group	Biological: the recombinant SARS-CoV-2 S-Trimer vaccine/inactivated SARS-CoV-2 vaccine; one booster dose intramuscularly in the deltoid muscle of the upper arm.
Active Comparator: ICV booster group	Biological: the recombinant SARS-CoV-2 S-Trimer vaccine/inactivated SARS-CoV-2 vaccine; one booster dose intramuscularly in the deltoid muscle of the upper arm.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Treatment-Emergent Adverse Events	All adverse events within 30 minutes of booster immunization	within 30 minutes after booster immunization
Incidence of Treatment-Emergent Adverse Events	Solicited local/systemic AEs within 7 days of booster immunization	within 7 days of booster immunization
Incidence of Treatment-Emergent Adverse Events	Unsolicited local/systemic AEs within 28 days of booster immunization	within 28 days of booster immunization
humoral immunogenicity	The Geometric Mean Titer (GMT) of neutralizing antibody against Delta, Omicron BA.2.2 and Omicron BA.5.2 after the booster immunization	On Day 14 and Day 28 after booster immunization
humoral immunogenicity	The Geometric Mean Fold Rises (GMFR) of neutralizing antibody against Delta, Omicron BA.2.2 and Omicron BA.5.2 after the booster immunization	On Day 14 and Day 28 after booster immunization
humoral immunogenicity	The seroconversion rate of neutralizing antibody against Delta, Omicron BA.2.2 and Omicron BA.5.2 after the booster immunization	On Day 14 and Day 28 after booster immunization

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
humoral immunogenicity	The Geometric Mean Titer (GMT) of neutralizing antibody against Delta, Omicron BA.2.2 and Omicron BA.5.2 after the booster immunization	On 3rd month, 6th month after booster immunization
humoral immunogenicity	The Geometric Mean Fold Rises (GMFR) of neutralizing antibody against Delta, Omicron BA.2.2 and Omicron BA.5.2 after the booster immunization	On 3rd month, 6th month after booster immunization
The safety outcomes were the counts and percentages of AEs, including SAEs and AESIs within 12 months, changes in laboratory safety parameters on the 3rd day following booster vaccination in comparison to baseline.	The safety outcomes were the counts and percentages of AEs, including severe adverse events (SAEs) and adverse of special interest (AESIs) within 12 months, changes in laboratory safety parameters on the 3rd day following booster vaccination in comparison to baseline.	12 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
exploratory endpoints	Proportion of CD4+ cell subsets	on 0, 14 days, 3 months, 6 months after booster immunization
exploratory endpoints	Proportion of CD8+ cell subsets	on 0, 14 days, 3 months, 6 months after booster immunization
exploratory endpoints	Expression level of IFN-γ	on 0, 14 days, 3 months, 6 months after booster immunization

Collaborators and Investigators

• Sponsor: Binhui Biopharmaceutical Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Actual): July 13, 2022
• Primary Completion (Actual): September 13, 2023
• Study Completion (Actual): September 13, 2023

Study Registration Dates

• First Submitted: January 10, 2023
• First Submitted That Met QC Criteria: January 28, 2023
• First Posted (Actual): February 8, 2023

Study Record Updates

• Last Update Posted (Actual): July 28, 2025
• Last Update Submitted That Met QC Criteria: July 24, 2025
• Last Verified: January 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Immunologic Factors; Physiological Effects of Drugs; Vaccines
• Other Study ID Numbers: BS033VX-001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No