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.

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.

Safety and immunogenicity of an inactivated whole virion SARS-CoV-2 vaccine, TURKOVAC, in healthy adults: Interim results from randomised, double-blind, placebo-controlled phase 1 and 2 trials.

BACKGROUND: Development of safe and effective vaccine options is crucial to the success of fight against COVID-19 pandemic. Herein, we report interim safety and immunogenicity findings of the phase 1&2 trials of ERUCoV-VAC, an inactivated whole virion SARS-CoV-2 vaccine. METHODS: Double-blind, randomised, single centre, phase 1 and 2 trials included SARS-CoV-2 seronegative healthy adults aged 18-55 years (18-64 in phase 2). All participants, except the first 4 in phase 1 who received ERUCoV-VAC 3 µg or 6 µg unblinded and monitored for 7 days for safety purposes, were assigned to receive two intramuscular doses of ERUCoV-VAC 3 µg or 6 µg (an inactivated vaccine containing alhydrogel as adjuvant) or placebo 21 days apart (28 days in phase 2) according to computer-generated randomisation schemes. Both trials are registered at ClinicalTrials.gov (phase 1, NCT04691947 and phase 2, NCT04824391). RESULTS: Forty-four participants (3 µg [n:17], 6 µg [n:17], placebo [n:10]) in phase 1 and 250 (3 µg [n:100], 6 µg [n:100], placebo [n:50]) in phase 2 received ≥1 dose. In phase 1 trial, 25 adverse events AEs (80 % mild) occured in 15 participants (34.1 %) until day 43. There was no dose-response relationship noted in safety events in ERUCoV-VAC recipients (p = 0.4905). Pain at injection site was the most common AE (9/44;20.5 %). Both doses of ERUCoV-VAC 3 µg and 6 µg groups were comparable in inducing SARS-CoV-2 wild-type neutralising antibody (MNT50): GMTs (95 %CI) were 8.3 (6.4-10.3) vs. 8.6 (7.0-10.2) at day 43 (p = 0.7357) and 9.7 (6.0-13.4) vs. 10.8 (8.8-12.8) at day 60 (p = 0.8644), respectively. FRNT50 confirmed MNT50 results: SARS-CoV-2 wild-type neutralising antibody GMTs (95 %CI) were 8.4 (6.3-10.5) vs. 9.0 (7.2-10.8) at day 43 (p = 0.5393) and 11.0 (7.0-14.9) vs. 12.3 (10.3-14.5) at day 60 (p = 0.8578). Neutralising antibody seroconversion rates (95 %CI) were 86.7 % (59.5-98.3) vs 94.1 % (71.3-99.8) at day 43 (p = 0.8727) and 92.8 % (66.1-99.8) vs. 100 % (79.4-100.0) at day 60 (p = 0.8873), in ERUCoV-VAC 3 µg and 6 µg groups, respectively. In phase 2 trial, 268 AEs, (67.2 % moderate in severity) occured in 153 (61.2 %) participants. The most common local and systemic AEs were pain at injection site (23 events in 21 [8.4 %] subjects) and headache (56 events in 47 [18.8 %] subjects), respectively. Pain at injection site was the only AE with a significantly higher frequency in the ERUCoV-VAC groups than in the placebo arm in the phase 2 study (p = 0.0322). ERUCoV-VAC groups were comparable in frequency of AEs (p = 0.4587). ERUCoV-VAC 3 µg and 6 µg groups were comparable neutralising antibody (MNT50): GMTs (95 %CI) were 30.0 (37.9-22.0) vs. 34.9 (47.6-22.1) at day 43 (p = 0.0666) and 34.2 (23.8-44.5) and 39.6 (22.7-58.0) at day 60, (p = 0.2166), respectively. FRNT50 confirmed MNT50 results: SARS-CoV-2 wildtype neutralising antibody GMTs were 28.9 (20.0-37.7) and 30.1 (18.5-41.6) at day 43 (p = 0.3366) and 34.2 (23.8-44.5) and 39.6 (22.7-58.0) at day 60 (p = 0.8777). Neutralising antibody seroconversion rates (95 %CI) were 95.7 % (91.4-99.8) vs. 98.9 % (96.9-100.0) at day 43 (p = 0.8710) and 96.6 % (92.8-100.0) vs 98.9 % (96.7-100.0) at day 60 (p = 0.9129) in ERUCoV-VAC 3 µg and 6 µg groups, respectively. CONCLUSIONS: Two-dose regimens of ERUCoV-VAC 3 µg and 6 µg 28 days both had an acceptable safety and tolerability profile and elicited comparable neutralising antibody responses and seroconversion rates exceeding 95 % at day 43 and 60 after the first vaccination. Data availability Data will be made available on request.

Development of an Inactivated Vaccine against SARS CoV-2.

The rapid spread of SARS-CoV-2 with its mutating strains has posed a global threat to safety during this COVID-19 pandemic. Thus far, there are 123 candidate vaccines in human clinical trials and more than 190 candidates in preclinical development worldwide as per the WHO on 1 October 2021. The various types of vaccines that are currently approved for emergency use include viral vectors (e.g., adenovirus, University of Oxford/AstraZeneca, Gamaleya Sputnik V, and Johnson & Johnson), mRNA (Moderna and Pfizer-BioNTech), and whole inactivated (Sinovac Biotech and Sinopharm) vaccines. Amidst the emerging cases and shortages of vaccines for global distribution, it is vital to develop a vaccine candidate that recapitulates the severe and fatal progression of COVID-19 and further helps to cope with the current outbreak. Hence, we present the preclinical immunogenicity, protective efficacy, and safety evaluation of a whole-virion inactivated SARS-CoV-2 vaccine candidate (ERUCoV-VAC) formulated in aluminium hydroxide, in three animal models, BALB/c mice, transgenic mice (K18-hACE2), and ferrets. The hCoV-19/Turkey/ERAGEM-001/2020 strain was used for the safety evaluation of ERUCoV-VAC. It was found that ERUCoV-VAC was highly immunogenic and elicited a strong immune response in BALB/c mice. The protective efficacy of the vaccine in K18-hACE2 showed that ERUCoV-VAC induced complete protection of the mice from a lethal SARS-CoV-2 challenge. Similar viral clearance rates with the safety evaluation of the vaccine in upper respiratory tracts were also positively appreciable in the ferret models. ERUCoV-VAC has been authorized by the Turkish Medicines and Medical Devices Agency and has now entered phase 3 clinical development (NCT04942405). The name of ERUCoV-VAC has been changed to TURKOVAC in the phase 3 clinical trial.

Isolation and characterization of severe acute respiratory syndrome coronavirus 2 in Turkey.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and associated with severe respiratory illness emerged in Wuhan, China, in late 2019. The virus has been able to spread promptly across all continents in the world. The current pandemic has posed a great threat to public health concern and safety. Currently, there are no specific treatments or licensed vaccines available for COVID-19. We isolated SARS-CoV-2 from the nasopharyngeal sample of a patient in Turkey with confirmed COVID-19. We determined that the Vero E6 and MA-104 cell lines are suitable for supporting SARS-CoV-2 that supports viral replication, development of cytopathic effect (CPE) and subsequent cell death. Phylogenetic analyses of the whole genome sequences showed that the hCoV-19/Turkey/ERAGEM-001/2020 strain clustered with the strains primarily from Australia, Canada, England, Iran and Kuwait and that the cases in the nearby clusters were reported to have travel history to Iran and to share the common unique nucleotide substitutions.