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.
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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
PREVENTION
Masking
NONE
Enrollment
2,052
Lipid nanoparticle (LNP)-encapsulated mRNA SARS-CoV-2 vaccine, 30 μg mRNA/0.3 mL, single intramuscular dose.
Jiangsu Provincial Center for Disease Control and Prevention
Nanjing, China
Geometric mean titer (GMT) of neutralizing antibodies in the immunogenicity subgroup
Measured in the immunogenicity subgroup at 14 days after booster immunization.
Time frame: 14 days after booster immunization
Incidence of serious adverse events (SAEs)
Serious adverse events monitored for 6 months after the booster administration.
Time frame: Within 6 months after the booster administration
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
Time frame: Day 14 after booster immunization
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
Time frame: Month 3 after booster immunization
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
Time frame: Month 6 after booster immunization
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
Time frame: Day 14 after booster immunization
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
Time frame: Month 3 after booster immunization
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
Time frame: Month 6 after booster immunization
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.
Time frame: Day 14 after booster immunization
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.
Time frame: Month 3 after booster immunization
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.
Time frame: Month 6 after booster immunization
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.
Time frame: Day 14 after booster immunization
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.
Time frame: Month 3 after booster immunization
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.
Time frame: Month 6 after booster immunization
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