• Clinical and Experimental Vaccine Research
• /
• v.13 no.4
• /
• pp.329-337
• /
• 2024

Purpose: This study evaluated the safety and immunogenicity of the PIKA-adjuvanted recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein subunit vaccine as a booster dose for healthy adults who had previously received two or more doses of an inactivated coronavirus disease 2019 (COVID-19) vaccine. Materials and Methods: The study was a phase II multicenter, double-blinded, comparatorcontrolled, randomized trial. Participants were randomly assigned to receive either the PIKA COVID-19 vaccine booster dose or an inactivated COVID-19 vaccine (Sinovac, China). Safety was assessed based on adverse events, while immunogenicity was measured by neutralizing antibodies against SARS-CoV-2 and serum immunoglobulin G (IgG) levels. Data on safety and immunogenicity were collected in the short-term (within 14 days after the booster dose) and long-term (from 90 to 365 days after the booster dose). Results: The PIKA-adjuvanted vaccine demonstrated a significant increase in neutralizing antibodies against the Omicron variant (geometric mean ratio [GMR]=2.0 on day 7, p-value <0.001; GMR=2.7 on day 14, p-value <0.001) and the wild type SARS-CoV-2 virus (GMR=2.3 on day 7, p-value <0.001; GMR=2.8 on day 14, p-value<0.001) in the early post-vaccination period when compared to the inactivated vaccine. Additionally, the PIKA COVID-19 vaccine showed higher seroconversion rates for neutralizing antibodies against both variants during the first 14 days post-vaccination. However, there were no significant differences in neutralizing antibody levels between the two vaccines from day 90 to day 360 post-vaccination. Serum IgG antibody levels for the PIKA COVID-19 vaccine were also higher throughout the study period. The incidence of adverse events was slightly higher in the PIKA COVID-19 group, with the most common events being pain at the injection site and headache. All adverse events were mild or moderate, with no reports of severe or life-threatening adverse events in either group. Conclusion: The PIKA COVID-19 vaccine, when administered as a booster dose, showed promising short- and long-term immunogenicity with no emergent safety issues identified. The booster dose of the PIKA COVID-19 vaccine elicited a robust immune response against various SARS-CoV-2 variants and provided some seroprotection for up to 360 days (ClinicalTrials. gov registration number: NCT05463419).

• Clinical and Experimental Vaccine Research
• /
• v.13 no.4
• /
• pp.315-328
• /
• 2024

Purpose: This phase I study aimed to assess the safety, tolerability, and immunogenicity of the PIKA-adjuvanted recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein subunit vaccine in healthy adults aged 18 years and older. Materials and Methods: This is a phase I, open-label, dose-escalation study at three dose levels (5 ㎍, 10 ㎍, and 20 ㎍) of the PIKA coronavirus disease 2019 (COVID-19) vaccine administered intramuscularly. The three vaccine arms are (A) subjects who have never received any COVID-19 vaccination or have had COVID-19 infection for >6 months prior to enrolment; (B1) subjects whose COVID-19 primary vaccination series was completed with an inactivated COVID-19 vaccine; and (B2) subjects whose primary series was completed with messenger RNA COVID-19 vaccine. Results: Subjects who reported solicited adverse events (AEs) within seven days post-vaccination ranged from 35% to 60% within each vaccine arm. Most solicited AEs were mild local pain and tenderness. Systemic solicited AEs were only reported in Arm A. In all three vaccine arms, neutralizing antibody geometric mean titers were highest at day 28 (Arms B1 and B2) or day 35 (Arm A) than at baseline for all dose levels against the Wuhan (wild original SARS-CoV-2 virus, Wuhan-Hu-1), Delta (B.1.617.2), and Omicron (B.1.1.529) variants. These were sustained at day 183. Seroconversion rates at day 35 (Arm A, 85.7%-92.9%) or day 183 (Arms B1, 90.9%-100.0%, and B2, 18.2%-36.4%) and geometric mean fold rises were highest in the 5-㎍ dose level against all three variants. Conclusion: The PIKA-adjuvanted recombinant SARS-CoV-2 S protein subunit vaccine showed promising immunogenicity profile with no safety concerns. A dose-dependent immune response was observed, with slight advantages seen in low-dose (5 ㎍ and 10 ㎍) groups (ClinicalTrials.gov registration number: NCT05305300).

• Clinical and Experimental Vaccine Research
• /
• v.13 no.4
• /
• pp.301-308
• /
• 2024

Purpose: The effects of coronavirus disease 2019 vaccination on fertility and pregnancy have turned out to be a main topic of public attention. Inactivated or recombinant protein vaccines are a reliable and safe method but mostly suffer from weak immunogenicity just in case formulated with a suitable adjuvant. The purpose of this research was to assess the impacts of new SpikoGen subunit vaccine administration during pregnancy on organogenesis in the rat fetus, which is a novel achievement in teratogenesis studies. Materials and Methods: In the first group (G1) animals received normal saline. A dose of 25 ㎍ of the vaccine was administered to groups of rats as follows: groups 2, 3, 4, and 5 received two doses of vaccine on different days before and after start of pregnancy. On day 21, after the caesarean process, the effects of the vaccine were estimated by morphological, skeletal, and histological studies. Results: Administration of the SpikoGen vaccine had no significant effect on weight, head diameter, tail length, and length of the fetuses to their tail. There were no malformations, toes and legs were fully developed, and all internal organs of the fetus were completely formed. Also, there was no difference in the overall skeletal opacity and density between the control and treatment groups. Conclusion: The results of this study indicated no negative impacts of the vaccine administration during pregnancy on developing of fetuses in rats.