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COVID-19

COVID-19 Vaccine Safety and Immunogenicity Data Revealed in New Study

Strategic Insights

— 2 min read

A recent report from Saskatoon, Canada, has published research findings on the safety and immunogenicity of a recombinant protein vaccine for COVID-19. The study, conducted by a team of researchers at the University of Saskatchewan, aimed to assess the safety and immunogenicity of a vaccine composed of the S1 subunit of the spike protein of SARS-CoV-2, formulated with the oil-in-water adjuvant Sepivac SWETM. The study enrolled 61 healthy adults, with no known prior exposure to SARS-CoV-2 virus or vaccines, into two cohorts based on age: 18-54 years old (n = 34) and 55+ years (n = 27).

Key Takeaways:

  • The study demonstrated that the vaccine, COVAC-2, was safe and induced high levels of both antigen-specific binding and neutralizing antibodies by Day 42-56, with levels beginning to wane by Day 120.
  • The most common adverse events were injection site pain, generalized muscle aches, and headaches in all dose levels and age groups, with most events being grade 1 and 2 in severity.
  • Two doses of vaccine were required for seroconversion in both 18-54 and 55+ cohorts, with 100% of participants seroconverting by Day 42 in the 18-54 cohort and 88% of participants by Day 42 in the 55+ cohort.
  • No clear T cell response was detected when measuring IFN gamma or IL-5 in peripheral blood mononuclear cells following stimulation with SARS-CoV-2 peptides.
  • The study was funded by Prairies Economic Development Canada, Government of Saskatchewan through Innovation Saskatchewan, Coalition for Epidemic Preparedness Innovations (CEPI), Canada Foundation for Innovation, Gida Tarim Ve Hayvancilik Bakanligi.

Statistics:

  • 61 healthy adults were enrolled in the study, with 34 in the 18-54 years old cohort and 27 in the 55+ years old cohort.
  • 817 IU/mL and 168 IU/mL were the geometric mean of S1 subunit-specific humoral binding and neutralizing antibody titres, respectively, in groups vaccinated with COVAC-2 between study Day 42 and 56.
  • Seroconversion in both 18-54 and 55+ cohorts required two doses of vaccine, with 100% of participants seroconverting by Day 42 in the 18-54 cohort and 88% of participants by Day 42 in the 55+ cohort.
  • Most adverse events were grade 1 and 2 in severity, with one participant in the 100 μg dose group reporting grade 3 adverse events.

Sources:

  • NewsRx. Data on COVID-19 Reported by Researchers at University of Saskatchewan (Safety and Immunogenicity of Covac-2, a Sepivac Swetm Adjuvanted Sars-cov-2 Recombinant Protein Vaccine In Healthy Adults; a Randomized Controlled First-in-human ...). Proteomics Weekly. October 20, 2025; p 276.
  • Safety and Immunogenicity of Covac-2, a Sepivac Swetm Adjuvanted Sars-cov-2 Recombinant Protein Vaccine In Healthy Adults; a Randomized Controlled First-in-human Dose-escalation Trial. Vaccine, 2025;64.

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