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COVID-19Phase 4SYS6006NCT07834073

Immunogenicity and Safety of a Single Dose of mRNA SARS-CoV-2 Vaccine in Chinese Adults With Hybrid Immunity

A Phase 4 study testing SYS6006 in people with COVID-19 and SARS-CoV-2 Infection, run by Jiangsu Province Centers for Disease Control and Prevention at 1 site in China.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This is a multicentre post-marketing cohort study to evaluate the immunogenicity and safety of a single dose of mRNA SARS-CoV-2 vaccine SYS6006 in Chinese adults predominantly with hybrid immunity. Read more about this study

Who is it for?
Ages 18 years and olderHealthy volunteers can take part
Conditions the study is for
COVID-19, SARS-CoV-2 Infection
What is being tested?
SYS6006
Could I receive a placebo?
No, everyone receives an active treatment
How many people
2,052 participants
Where
1 siteChina
Study dates
23 May 2023to 28 Feb 2024
Phase
Phase 4
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Adults aged 18 years and over, including the elderly over 60 years and those with general underlying diseases.
  • At least 4 months since the last SARS-CoV-2 infection (or never infected), and at least 6 months since the last COVID-19 vaccination.
  • Able and willing to comply with the study procedures and to provide written informed consent.

Who cannot join

  • Suspected COVID-19 symptoms on the day of enrollment (e.g., dry/sore throat, cough).
  • Positive SARS-CoV-2 antigen rapid test at enrollment.
  • Prior receipt of the first COVID-19 booster dose .
  • History of severe adverse reactions or anaphylaxis related to vaccination, or known severe allergy to any vaccine component.
  • Pregnant or lactating women.
  • Any other condition that, in the investigator's judgment, makes the individual unsuitable for the study.
  • -

Trial locations and contacts

1 site in 1 country.

China1 site

  • Jiangsu Provincial Center for Disease Control and Prevention

    Nanjing

Other trials in China

About this study

Official title: Immunogenicity and Safety of a Single Dose of mRNA COVID-19 Vaccine in Chinese Adults With Hybrid Immunity: a Multicentre, Open-label, Single-arm, Post-marketing Study

This is a multicentre post-marketing cohort study to evaluate the immunogenicity and safety of a single dose of mRNA SARS-CoV-2 vaccine SYS6006 in Chinese adults predominantly with hybrid immunity. A total of 2,052 adults aged 18 years and older who received one dose of SYS6006 were monitored for serious adverse events (SAEs) for 6 months. The first 60 participants comprised an immunogenicity subgroup, with blood samples collected before vaccination and at day 14, month 3, and month 6 post-vaccination to assess humoral and cellular immune responses.

Read the detailed description

This study evaluated the immunogenicity and safety of a single dose of the mRNA SARS-CoV-2 vaccine SYS6006 (CSPC Megalith Biopharmaceutical Co., Ltd, Shijiazhuang, China) in Chinese adults aged 18 years and older predominantly with hybrid immunity against COVID-19. Between May and August 2023, 2,052 adults in five cities of Jiangsu Province, China (Taizhou, Changzhou, Lianyungang, Suqian, and Wuxi) received one intramuscular dose of SYS6006 (30 μg mRNA/0.3 mL) and were followed for 6 months to monitor serious adverse events (SAEs). The first 60 participants comprised the immunogenicity subgroup; serum and peripheral blood mononuclear cells (PBMCs) were collected before vaccination and at day 14, month 3, and month 6 post-vaccination. Immunogenicity assessments included pseudovirus neutralizing antibody geometric mean titres (GMTs) against wild-type (WT), BA.4/5, and XBB.1.16; receptor-binding domain (RBD)-specific IgG and IgA; ACE2-RBD binding inhibition; Fc-mediated effector functions (ADCP, ADCC, ADNP); and IFN-γ/IL-2 ELISpot responses.

Being tested
SYS6006
Keywords
mRNA vaccine, COVID-19 vaccines, SYS6006, Omicron variant, Hybrid immunity, Post-marketing surveillance, Immunogenicity, Safety
Medical subject headings
COVID-19

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • SYS6006Biological

    Lipid nanoparticle (LNP)-encapsulated mRNA SARS-CoV-2 vaccine, 30 μg mRNA/0.3 mL, single intramuscular dose.

Study groups in NCT07834073
Study groupRoleWhat they receive
SYS6006 single-dose recipientsExperimentalParticipants in this arm received a single intramuscular dose of SYS6006 (CSPC Megalith Biopharmaceutical Co., Ltd, Shijiazhuang, China), a lipid nanoparticle (LNP)-encapsulated mRNA SARS-CoV-2 vaccine containing 30 μg mRNA in 0.3 mL. The vaccine encodes the full-length spike (S) protein of the SARS-CoV-2 Omicron variant and harbours key mutations from Delta, Omicron BA.4/5 and BF.7, and was administered via intramuscular injection into the deltoid muscle of the upper arm.
Receives: Biological: SYS6006

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Geometric mean titer (GMT) of neutralizing antibodies in the immunogenicity subgroup

    Measured in the immunogenicity subgroup at 14 days after booster immunization.

    Measured: 14 days after booster immunization

  2. Incidence of serious adverse events (SAEs)

    Serious adverse events monitored for 6 months after the booster administration.

    Measured: Within 6 months after the booster administration

Secondary outcomes (12)

  1. Geometric mean concentration (GMC) of serum RBD-specific IgG

    GMC of serum RBD-specific IgG antibodies against WT and Omicron variants, measured by ELISA after booster immunization

    Measured: Day 14 after booster immunization

  2. Geometric mean concentration (GMC) of serum RBD-specific IgG

    GMC of serum RBD-specific IgG antibodies against WT and Omicron variants, measured by ELISA after booster immunization

    Measured: Month 3 after booster immunization

  3. Geometric mean concentration (GMC) of serum RBD-specific IgG

    GMC of serum RBD-specific IgG antibodies against WT and Omicron variants, measured by ELISA after booster immunization

    Measured: Month 6 after booster immunization

  4. Geometric mean concentration (GMC) of serum RBD-specific IgA

    GMC of serum RBD-specific IgA antibodies against WT and Omicron variants, measured by ELISA after booster immunization

    Measured: Day 14 after booster immunization

  5. Geometric mean concentration (GMC) of serum RBD-specific IgA

    GMC of serum RBD-specific IgA antibodies against WT and Omicron variants, measured by ELISA after booster immunization

    Measured: Month 3 after booster immunization

  6. Geometric mean concentration (GMC) of serum RBD-specific IgA

    GMC of serum RBD-specific IgA antibodies against WT and Omicron variants, measured by ELISA after booster immunization

    Measured: Month 6 after booster immunization

  7. ACE2-RBD binding inhibition rate

    Rate of inhibition of ACE2-RBD binding in serum, measured by surrogate virus neutralization / competitive binding assay after booster immunization.

    Measured: Day 14 after booster immunization

  8. ACE2-RBD binding inhibition rate

    Rate of inhibition of ACE2-RBD binding in serum, measured by surrogate virus neutralization / competitive binding assay after booster immunization.

    Measured: Month 3 after booster immunization

  9. ACE2-RBD binding inhibition rate

    Rate of inhibition of ACE2-RBD binding in serum, measured by surrogate virus neutralization / competitive binding assay after booster immunization.

    Measured: Month 6 after booster immunization

  10. Antigen-specific T-cell response measured by ELISpot

    Frequency of antigen-specific T cells (spot-forming cells) in peripheral blood measured by ELISpot assay after booster immunization.

    Measured: Day 14 after booster immunization

  11. Antigen-specific T-cell response measured by ELISpot

    Frequency of antigen-specific T cells (spot-forming cells) in peripheral blood measured by ELISpot assay after booster immunization.

    Measured: Month 3 after booster immunization

  12. Antigen-specific T-cell response measured by ELISpot

    Frequency of antigen-specific T cells (spot-forming cells) in peripheral blood measured by ELISpot assay after booster immunization.

    Measured: Month 6 after booster immunization

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted22 Sep 2026
  2. Study start23 May 2023
  3. Primary completion28 Feb 2024
  4. Study completion28 Feb 2024

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 4
Primary purpose
Prevention
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
2,052 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07834073
Sponsor's protocol ID
JSIIT007
Acronym
SYS6006
Status last verified
Sep 2026
First submitted
17 Sep 2026
Last updated
22 Sep 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 4 study testing SYS6006 in people with COVID-19 and SARS-CoV-2 Infection, run by Jiangsu Province Centers for Disease Control and Prevention at 1 site in China.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 3 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 22 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Geometric mean titer (GMT) of neutralizing antibodies in the immunogenicity subgroup (time frame: 14 days after booster immunization). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07834073.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Sep 2026.

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