Open label phase I/II clinical trial and predicted efficacy of SARS-CoV-2 RBD protein vaccines SOBERANA 02 and SOBERANA Plus in children (preprint)

ObjectivesTo evaluate heterologous scheme in children 3-18 y/o using two SARS-CoV-2 r-RBD protein vaccines. MethodsA phase I/II open-label, adaptive and multicenter trial evaluated the safety and immunogenicity of two doses of SOBERANA02 and a heterologous third dose of SOBERANA Plus in 350 children 3-18 y/o in Havana Cuba. Primary outcomes were safety (in phase I) and safety/immunogenicity (in phase II) measured by anti-RBD IgG ELISA, molecular and live-virus neutralization tests and specific T-cells response. An immunobridging and prediction of efficacy were additional analysis. ResultsLocal pain was the unique adverse event with >10% frequency, none was serious or severe. Two doses of SOBERANA 02 elicited humoral immune response similar to natural infection; the third dose increased significantly the response in all children, similar to that achieved in vaccinated young adults and higher than in convalescents children. The neutralizing titer was evaluated in a participants subset: all had neutralizing antibodies vs. alpha and delta; 97.9% vs. beta. GMT was 173.8 (CI 95% 131.7; 229.5) vs. alpha, 142 (CI 95% 101.3; 198.9) vs. delta and 24.8 (CI 95% 16.8; 36.6) vs. beta. An efficacy over 90% was estimated. ConclusionHeterologous scheme was safe and immunogenic in children 3-18 y/o. Trial registry: https://rpcec.sld.cu/trials/RPCEC00000374

Safety and immunogenicity of anti-SARS CoV-2 conjugate vaccine SOBERANA 02 in a two-dose or three-dose heterologous scheme in adults: Phase IIb Clinical Trial (preprint)

Background: We report results of immunogenicity, safety and reactogenicity of SOBERANA 02 in a two-dose or three-dose heterologous scheme in adults in a phase IIb clinical trial. Method: This phase IIb trial was designed as parallel, multicentre, adaptive, double blind, randomized and placebo-controlled. Subjects (N=810) aged 19-80 years were randomized to receive two doses of the recombinant SARS CoV-2 receptor binding domain (RBD) conjugated to tetanus toxoid (SOBERANA 02) and a third dose of dimeric RBD (SOBERANA Plus) 28 days apart; two production batches of active ingredient of SOBERANA 02 were evaluated. Primary outcome was the percentage of seroconverted subjects with [≥]4-fold the anti-RBD IgG concentration. Secondary outcomes were safety, reactogenicity and neutralizing antibodies. Results: Seroconversion rate in vaccinees was respectively 76.3 and 96.8% after two or three doses, compared with 7.3% in placebo group. Anti-RBD IgG increased significantly after first and second dose of SOBERANA 02 respect to placebo group; and the third dose with SOBERANA Plus boosts the response compared to the second dose. Neutralizing IgG antibodies were detected against D614G and VOCs , {beta} and {delta}. Specific and functional antibodies were detected until 7-8 months after the third dose. The frequency of serious adverse events (AEs) associated with vaccination was very low (0.1%); with only one serious AE consistent with vaccination. Local pain was the most frequent AE. Conclusions: Two doses of SOBERANA 02 were well tolerated, safe an immunogenic in adults aged 19-80 years old. The heterologous combination with a third dose of SOBERANA Plus increased neutralizing antibodies, detectable 7-8 months after the third dose. Trial registry: https://rpcec.sld.cu/trials/RPCEC00000347

Safety and Immunogenicity of anti-SARS CoV-2 vaccine SOBERANA 02 in homologous or heterologous scheme. (preprint)

Background SOBERANA 02 is a COVID19 conjugate vaccine candidate based on SARS CoV2 recombinant RBD conjugated to tetanus toxoid. SOBERANA Plus antigen is dimericRBD. Here we report safety, reactogenicity and immunogenicity from phase I and IIa clinical trials using two doses SOBERANA 02 (homologous protocol) and three doses (homologous) or heterologous (with SOBERANA Plus) protocols. Method We performed an open label, monocentric, sequential and adaptive phase I for evaluating safety, reactogenicity and exploring immunogenicity of SOBERANA 02 in two formulations (15 and 25 microg) in 40 subjects, 19 to 59 years old. Phase IIa was open label including 100 volunteers 19 to 80 years, receiving two doses of SOBERANA 02 25 microg. In both trials, half of volunteers received a third dose of SOBERANA 02, half received a heterologous dose of SOBERANA Plus 50 microg. Primary outcomes were safety and reactogenicity. The secondary outcome was vaccine immunogenicity evaluated by anti RBD IgG ELISA, molecular neutralization test of RBD:hACE2 interaction, live virus neutralization test and specific T cells response. Results The most frequent AE was local pain, other AEs had frequencies lower than 5%. No serious related AEs were reported. Phase IIa confirmed the safety results in 60 to 80 years subjects. In phase I SOBERANA 02 25 microg elicited higher immune response than SOBERANA 02 15 microg; in consequence, the higher dose progressed to phase IIa. Phase IIa results confirmed the immunogenicity of SOBERANA 02 25 microg. even in 60 to 80 age range. Two doses of SOBERANA02 25 microg elicited an immune response similar to that of the Cuban Convalescent Serum Panel; it was higher after both the homologous and heterologous third doses; the heterologous scheme showing a higher immunological response. Conclusions SOBERANA 02 was safe and immunogenic in persons aged 19 to 80 years, eliciting neutralizing antibodies and specific T cell response. Highest immune responses were obtained in the heterologous three doses protocol. Trial registry: https://rpcec.sld.cu/trials/RPCEC00000340 and https://rpcec.sld.cu/trials/RPCEC00000347

A randomized, double-blind phase I clinical trial of two recombinant dimeric RBD COVID-19 vaccine candidates: safety, reactogenicity and immunogenicity (preprint)

Background The Receptor Binding Domain (RBD) of the SARS-CoV-2 spike protein is the target for many COVID-19 vaccines. Here we report results for phase 1 clinical trial of two COVID-19 vaccine candidates based on recombinant dimeric RBD (d-RBD). Methods We performed a randomized, double-blind, phase I clinical trial in the National Centre of Toxicology in Havana. Sixty Cuban volunteers aged 19-59 years were randomized into three groups (20 subjects each): 1) FINLAY-FR-1 (50 mcg d-RBD plus outer membrane vesicles from N. meningitidis ); 2) FINLAY-FR-1A-50 mcg d-RBD (three doses); 3) FINLAY-FR-1A-25 mcg d-RDB (three doses). The FINLAY-FR-1 group was randomly divided to receive a third dose of the same vaccine candidate (homologous schedule) or of FINLAY-FR-1A-50 (heterologous schedule). The primary outcomes were safety and reactogenicity. The secondary outcome was vaccine immunogenicity. Humoral response at baseline and following each vaccination was evaluated using live-virus neutralization test, anti-RBD IgG ELISA and in-vitro neutralization test of RBD:hACE2 interaction. Results Most adverse events were of mild intensity (63.5%), solicited (58.8%), and local (61.8%); 69.4% with causal association with vaccination. Serious adverse events were not found. The FINLAY-FR-1 group reported more adverse events than the other two groups. After the third dose, anti-RBD seroconversion was 100%, 94.4% and 90% for the FINLAY-FR-1, FINLAY-FR-1A-50 and FINLAY-FR-1A-25 respectively. The in-vitro inhibition of RBD:hACE2 interaction increased after the second dose in all formulations. The geometric mean neutralizing titres after the third dose rose significantly in the group vaccinated with FINLAY-FR-1 with respect to the other formulations and the COVID-19 Convalescent Serum Panel. No differences were found between FINLAY-FR-1 homologous or heterologous schedules. Conclusions Vaccine candidates were safe and immunogenic, and induced live-virus neutralizing antibodies against SARS-CoV-2. The highest values were obtained when outer membrane vesicles were used as adjuvant. Trial registry https://rpcec.sld.cu/en/trials/RPCEC00000338-En

A single dose of SARS CoV 2 FINLAY FR 1A dimeric RBD recombinant vaccine enhances neutralization response in COVID19 convalescents, with excellent safety profile. A preliminary report of an open-label phase 1 clinical trial (preprint)

We evaluated response to a single dose of the FINLAY FR 1A recombinant dimeric RBD base vaccine during a phase I clinical trial with 30 COVID 19 convalescents, to test its capacity for boosting natural immunity. This short report shows: a) an excellent safety profile one month after vaccination for all participants, similar to that previously found during vaccination of naive individuals; b) a single dose of vaccine induces a 20 fold increase in antibody response one week after vaccination and remarkably 4 fold higher virus neutralization compared to the median obtained for Cuban convalescent serum panel. These preliminary results prompt initiation of a phase II trial in order to establish a general vaccination protocol for convalescents.