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Sezer Z, Pavel STI, Inal A, Yetiskin H, Kaplan B, Uygut MA, Aslan AF, Bayram A, Mazicioglu M, Kalin Unuvar G, Yuce ZT, Aydin G, Kaya RK, Ates I, Kara A, Ozdarendeli A. Long-Term Immunogenicity and Safety of a Homologous Third Dose Booster Vaccination with TURKOVAC: Phase 2 Clinical Study Findings with 32-Week Post-Booster Follow-Up. Vaccines (Basel) 2024; 12:140. [PMID: 38400124 PMCID: PMC10893411 DOI: 10.3390/vaccines12020140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 01/19/2024] [Indexed: 02/25/2024] Open
Abstract
Vaccine-induced immunity wanes over time and warrants booster doses. We investigated the long-term (32 weeks) immunogenicity and safety of a third, homologous, open-label booster dose of TURKOVAC, administered 12 weeks after completion of the primary series in a randomized, controlled, double-blind, phase 2 study. Forty-two participants included in the analysis were evaluated for neutralizing antibodies (NAbs) (with microneutralization (MNT50) and focus reduction (FRNT50) tests), SARS-CoV-2 S1 RBD (Spike S1 Receptor Binding Domain), and whole SARS-CoV-2 (with ELISA) IgGs on the day of booster injection and at weeks 1, 2, 4, 8, 16, 24, and 32 thereafter. Antibody titers increased significantly from week 1 and remained higher than the pre-booster titers until at least week 4 (week 8 for whole SARS-CoV-2) (p < 0.05 for all). Seroconversion (titers ≥ 4-fold compared with pre-immune status) persisted 16 weeks (MNT50: 6-fold; FRNT50: 5.4-fold) for NAbs and 32 weeks for S1 RBD (7.9-fold) and whole SARS-CoV-2 (9.4-fold) IgGs. Nine participants (20.9%) tested positive for SARS-CoV-2 RT-PCR between weeks 8 and 32 of booster vaccination; none of them were hospitalized or died. These findings suggest that boosting with TURKOVAC can provide effective protection against COVID-19 for at least 8 weeks and reduce the severity of the disease.
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Affiliation(s)
- Zafer Sezer
- Department of Medical Pharmacology, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
- Good Clinical Practise Centre (IKUM), Erciyes University, Kayseri 38280, Türkiye
| | - Shaikh Terkis Islam Pavel
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
| | - Ahmet Inal
- Department of Medical Pharmacology, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
- Good Clinical Practise Centre (IKUM), Erciyes University, Kayseri 38280, Türkiye
| | - Hazel Yetiskin
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
| | - Busra Kaplan
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
| | - Muhammet Ali Uygut
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
| | - Ahmet Furkan Aslan
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
| | - Adnan Bayram
- Department of Anesthesiology and Reanimation, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
| | - Mumtaz Mazicioglu
- Department of Family Medicine, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
| | - Gamze Kalin Unuvar
- Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
| | - Zeynep Ture Yuce
- Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
| | - Gunsu Aydin
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
- Department of Microbiology, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
| | | | - Ihsan Ates
- Department of Internal Medicine, University of Health Sciences Ankara City Hospital, Ankara 06530, Türkiye
| | - Ates Kara
- Health Institutes of Türkiye (TUSEB), Istanbul 34718, Türkiye
- Department of Pediatrics, Pediatric Infectious Disease, Faculty of Medicine, Hacettepe University, Ankara 06430, Türkiye
| | - Aykut Ozdarendeli
- Vaccine Research, Development and Application Centre (ERAGEM), Erciyes University, Kayseri 38280, Türkiye
- Department of Microbiology, Faculty of Medicine, Erciyes University, Kayseri 38280, Türkiye
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