Immunogenicity and Safety of a Booster Dose of the SpikoGen COVID-19 Vaccine

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.