Article
Author: Valenzuela-Silva, Carmen  ; Vérez-Bencomo, Vicente  ; Palenzuela-Diaz, Ariel  ; Paredes-Moreno, Beatriz  ; Climent-Ruiz, Yanet  ; Espi-Ávila, Jennifer  ; Espino-Rojas, Niurka Tamara  ; Rodriguez-González, Meybis  ; Ramírez-Gonzalez, Ubel  ; Coviella-Artime, José Manuel  ; Ontivero-Pino, Ivis  ; Medinas-Santos, Gloria Margarita  ; Acosta-Martinez, Mario Alejandro  ; Dubed-Echevarría, Marta  ; Morffi-Cinta, Irania  ; Chen, Guang-Wu  ; Perez-Perez, Alina  ; Pérez-Rodríguez, Suzel  ; Reyes-Matienzo, Radamet  ; Mendoza-Hernández, Ivis  ; Martínez-Pérez, Marisel  ; Arteaga-García, Amaylid  ; Fontanies-Fernández, Marcos  ; Valera-Fernández, Rodrigo  ; Boggiano-Ayo, Tammy  ; Galano-Frutos, Evelyn  ; Enriquez-Puertas, Juliet  ; Quintero-Moreno, Lauren  ; Muñoz, Yaima  ; Hernández-Garcia, Tays  ; Acevedo-Martínez, Yosmel  ; Orosa-Vázquez, Ivette  ; Rodríguez, Misladys  ; Rivera, Daniel G.  ; Bergado-Baez, Gretchen  ; Santana-Mederos, Darielys  ; Garrido-Arteaga, Raine  ; Noa-Romero, Enrique  ; Garcés-Hechavarría, Aniurka  ; Baro-Roman, Gerardo  ; Doroud, Delaram  ; Domínguez-Pentón, Yeney Regla  ; Morales-Ruano, Susana  ; Estoque-Cabrera, Solangel  ; García-López, Elena  ; Pi-Estopiñán, Franciscary  ; Rodríguez-Castillo, Pedro Gabriel  ; Cruz-Sui, Otto  ; Alfaro-Guzmán, Ainadis  ; Gómez-Maceo, Yanet  ; García-Montero, Majela  ; González-Mugica, Raúl  ; Verdecia-Sánchez, Leslyhana  ; Lora-García, Janet  ; Cardoso-SanJorge, Félix  ; Sanchez-Ramirez, Belinda  ; García-Rivera, Dagmar  ; Santos-Vega, Bertha Leysi  ; Díaz-Hernández, Marianniz  ; Ojito-Magaz, Eduardo  ; Toledo-Romani, María Eugenia  ; García-Carmenate, Mayra  ; Pérez-Guevara, María Teresa  ; Rodríguez-Noda, Laura  ; Valdés-Balbín, Yury  ; Fernandez-Castillo, Sonsire  ; Brito-Pascual, Idalmis  ; Zulueta-Pérez, Lilian  ; Amoroto, Maité  ; Medina-Nápoles, Maite  ; Biglari, Alireza  ; Martínez-Bedoya, Dayle  ; García-Vega, Yanelda  ; Ávila-Cabreja, José Alejandro  ; Martínez-Rivera, Roselyn  ; Sarda-Rodriguez, Ileana Luisa  ; Cubas-Curbelo, Mailin  ; Guillén-Obregón, Berta 
BACKGROUNDSOBERANA 02 has been evaluated in phase I and IIa studies comparing homologous versus heterologous schedule (this one, including SOBERANA Plus). Here, we report results of immunogenicity, safety, and reactogenicity of SOBERANA 02 in a two- or three-dose heterologous scheme in adults.METHODPhase IIb was a parallel, multicenter, adaptive, double-blind, randomized, and placebo-controlled trial. Subjects (n = 810) aged 19-80 years were randomized to receive two doses of SARS-CoV-2 RBD conjugated to tetanus toxoid (SOBERANA 02) and a third dose of dimeric RBD (SOBERANA Plus) 28 days apart; two production batches of active ingredients of SOBERANA 02 were evaluated. Primary outcome was the percentage of seroconverted subjects with ≥4-fold the anti-RBD immunoglobulin G (IgG) concentration. Secondary outcomes were safety, reactogenicity, and neutralizing antibodies.FINDINGSSeroconversion rate in vaccinees was 76.3% after two doses and 96.8% after the third dose of SOBERANA Plus (7.3% in the placebo group). Neutralizing IgG antibodies were detected against D614G and variants of concern (VOCs) Alpha, Beta, Delta, and Omicron. Specific, functional antibodies were detected 7-8 months after the third dose. The frequency of serious adverse events (AEs) associated with vaccination was very low (0.1%). Local pain was the most frequent AE.CONCLUSIONSTwo doses of SOBERANA 02 were safe and immunogenic in adults. The heterologous combination with SOBERANA Plus increased neutralizing antibodies, detectable 7-8 months after the third dose.TRIAL REGISTRYhttps://rpcec.sld.cu/trials/RPCEC00000347 FUNDING: This work was supported by Finlay Vaccine Institute, BioCubaFarma, and the Fondo Nacional de Ciencia y Técnica (FONCI-CITMA-Cuba, contract 2020-20).