TURKOVAC Trials
TURKOVAC is the domestic Turkish inactivated SARS-CoV-2 vaccine developed at Erciyes University and advanced with the support of TÜSEB and the Türkiye Vaccine Institute. The booster dose efficacy and safety of this vaccine were evaluated through the Hybrid COV-RAPEL TR trial and large-scale adverse event analyses.
The Clinical Journey of a Domestic Turkish Vaccine
During the pandemic, vaccine independence became a strategic priority for Turkey. TURKOVAC — an inactivated whole-virion vaccine developed by the Erciyes University microbiology team (under the leadership of Prof. Dr. Aykut Özdarendeli) — was evaluated after its phase 1 and phase 2 stages as a booster dose in individuals primed with CoronaVac.
Two of these studies were published in international peer-reviewed journals and generated valuable immunological data for both the scientific community and regulators. From study design to vaccine logistics, from the electronic data capture system to randomization and telephone call systems, the entire infrastructure again ran under the Omega roof.
December 22, 2021: Türkiye Authorized Its First Domestic Vaccine
TURKOVAC became the first domestically developed COVID-19 vaccine to receive emergency use authorization in the history of Türkiye. Following the Ministry of Health authorization on December 22, 2021, the vaccine was opened for use by all citizens as a booster dose in the national vaccination program.
This authorization rested on the evidence generated by the trials described on this page, together with booster immunogenicity and safety data. On the road to emergency use authorizations for both vaccine programs, Omega data was decisive.
Hybrid COV-RAPEL TR
The booster trial: in healthy adults aged 18-60 primed with two doses of CoronaVac, the safety and immunogenicity of TURKOVAC versus CoronaVac booster doses were compared. A double-blind, randomized, controlled phase 2, multicenter design. Of 236 eligible volunteers, 222 were randomized between July 12 and September 10, 2021: 108 to the TURKOVAC arm and 114 to the CoronaVac arm.
Within 90-270 days after primary vaccination, protective neutralizing antibody titers had declined markedly — dropping below the 1/6 seropositivity threshold against the Wuhan variant in more than half of the participants. The booster dose rapidly and markedly re-stimulated antibody responses with both vaccines.
Neutralizing antibody positivity (1/6 threshold)
The TURKOVAC arm produced a markedly higher response against the Delta variant
IgG spike antibody positivity rates
Prior COVID and Adverse Events
A secondary analysis of the randomized, observer-blinded, non-inferiority study: in 1,266 participants aged 18-55, the impact of prior SARS-CoV-2 infection before the first dose on local and systemic adverse events after TURKOVAC and CoronaVac was evaluated.
27.7% of the participants had a history of COVID-19. Adverse event frequencies in the first 30 minutes and 24 hours were slightly higher among those with a COVID-19 history; none were severe. After the second dose the groups remained comparable, and both vaccines showed similar adverse event profiles within the first 30 minutes.
Safety and immunogenicity of inactive vaccines as booster doses for COVID-19 in Türkiye: A randomized trial
Omma A, Batirel A, Aydin M, ve ark. — DOI: 10.1080/21645515.2022.2122503
PubMed Record ↗The impact of previous SARS-CoV-2 infection on post-vaccine adverse events in individuals vaccinated with TURKOVAC or CoronaVac inactivated COVID-19 vaccines
Durusu Tanrıöver M, Altuntaş Aydın O, Güner R, ve ark. — DOI: 10.1080/21645515.2024.2346388
PubMed Record ↗