This was a randomized, two-armed, double-blind, placebo-controlled trial designed to evaluate the safety and immunogenicity of a booster dose of an adjuvanted recombinant SARS-CoV-2 spike protein subunit vaccine (SpikoGen) produced by CinnaGen Co. A total of 300 adult individuals received a single dose of either the SpikoGen vaccine or the saline placebo in a 5:1 ratio at 4 to 9 months after the second dose of a COVID-19 vaccine of any type. The injection was given in the deltoid muscle of the non-dominant arm. On day 14, the trial was unblinded, and the participants in the placebo group received a booster dose of the SpikoGen vaccine. For immunogenicity assessments, blood samples were collected on days 0 and 14 from all participants and on days 90 and 180 from those in the vaccine group only. For safety assessments, all participants were followed up for six months. Study hypotheses included: 1. A booster dose of the SpikoGen COVID-19 vaccine is safe and tolerable in adult subjects. 2. A booster dose of the SpikoGen COVID-19 vaccine induces strong immunogenicity against SARS-CoV-2 in adult subjects.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
300
SARS-CoV-2 recombinant spike protein (25 µg) with Advax-SM adjuvant (15 mg); a single intramuscular injection into the deltoid muscle of the non-dominant arm
0.9% sodium chloride (1 mL); a single intramuscular injection into the deltoid muscle of the non-dominant arm
Orchid Life Department, Orchid Pharmed Company
Tehran, Iran
Percentage of participants with seroconversion for SARS-CoV-2 neutralizing antibodies
As measured by ELISA
Time frame: 14 days after the booster dose
Incidence of solicited adverse events
Injection site pain, erythema, swelling, and induration, axillary swelling or tenderness ipsilateral to the side of injection, fever (oral temperature), headache, fatigue, myalgia, arthralgia, nausea, vomiting, and chills, as reported by the study participants on electronic diaries, and as defined using system organ classes and preferred terms of the Medical Dictionary for Regulatory Activities (MedDRA)
Time frame: For 7 days after the booster dose
Incidence of unsolicited adverse events
As reported by the study participants on electronic diaries, and as defined using system organ classes and preferred terms of the Medical Dictionary for Regulatory Activities (MedDRA)
Time frame: For 14 days after the booster dose
Incidence of serious adverse events (SAEs) and suspected unexpected serious adverse reaction (SUSARs)
As defined using system organ classes and preferred terms of the Medical Dictionary for Regulatory Activities (MedDRA)
Time frame: For 6 months after the booster dose
Geometric mean concentration (GMC) for S1 binding IgG antibodies
As measured by ELISA
Time frame: Days 0, 14, 90, and 180
Geometric mean fold rise (GMFR) for S1 binding IgG antibodies
As measured by ELISA
Time frame: 14 days after the booster dose
Percentage of participants with seroconversion for S1 binding IgG antibodies
As measured by ELISA
Time frame: 14 days after the booster dose
Percentage of participants with seroconversion for receptor-binding domain (RBD) binding IgG antibodies
As measured by ELISA
Time frame: 14 days after the booster dose
Geometric mean concentration (GMC) for receptor-binding domain (RBD) binding IgG antibodies
As measured by ELISA
Time frame: Days 0, 14, 90, and 180
Geometric mean fold rise (GMFR) for receptor-binding domain (RBD) binding IgG antibodies
As measured by ELISA
Time frame: 14 days after the booster dose
Geometric mean concentration (GMC) for SARS-CoV-2 neutralizing antibodies
As measured by ELISA
Time frame: Days 0, 14, 90, and 180
Geometric mean fold rise (GMFR) for SARS-CoV-2 neutralizing antibodies
As measured by ELISA
Time frame: 14 days after the booster dose
Change in T-cell IFN-γ secretion from baseline to 14 days after the booster dose
As measured by IGRA
Time frame: Days 0 and 14
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