Bio-Manguinhos/Fiocruz COVID-19 (mRNA) Vaccine Booster

The inclusion of cohorts, defined by dose, will be carried out in a staggered manner in the following order: Sentinel group 1 (25 μg dose): Analysis of reactogenicity and safety data from 5 participants, who will be included one at a time and evaluated 48 hours after administration of the investigational product. The safety data from these participants will be obtained 7 days after vaccination and evaluated by the CMDS to allow the inclusion of the remaining 25 participants from this dose, as well as the participants from the sentinel group of the 50 μg dose. Sentinel group 2 (50 μg dose): Analysis of reactogenicity and safety data from 5 participants, who will be included one at a time and evaluated 48 hours after administration of the investigational product. Safety data from these participants will be obtained 7 days after vaccination and evaluated by the CMDS to allow the inclusion of the remaining 25 participants from this dose, as well as the participants from the sentinel group of the 100 μg dose. Sentinel Group 3 (100 μg dose): Analysis of reactogenicity and safety data from 5 participants, who will be included one at a time and evaluated 48 hours after administration of the investigational product. Safety data from these participants will be obtained 7 days after vaccination and evaluated by the CMDS to allow the inclusion of the remaining 25 participants in this dose. At the end of this period, a formal cumulative safety review will be conducted by the Data and Safety Monitoring Committee (CMDS), which will evaluate all available safety data from the sentinel group, including: solicited and unsolicited adverse events; serious adverse events; severe adverse events; vital signs; laboratory data; and any other relevant clinical findings. The CMDS will issue a documented report recommending or not the continuation of the study. The study population will consist of 90 adult participants who received complete primary vaccination for COVID-19, and at least one additional booster dose, the last booster being an mRNA vaccine approved by ANVISA, administered at least 6 months prior to inclusion. The study design was based on the European Medicines Agency - EMA guideline, ANVISA-RDC 945/2024 and Law 14.874/2024 \[4\] and other phase I clinical studies of RNA-based vaccines for COVID-19. Data from this study will support decisions on whether the candidate vaccine should be further evaluated in advanced phase clinical trials, guide dose selection, and support platform development. If the monovalent candidate induces potentially protective immune responses with an acceptable safety profile, there may be potential to develop future multivalent vaccines to prevent COVID-19 disease based on this platform. The clinical study will begin immediately after ethical and regulatory approvals. The participant inclusion period is estimated to be 6 months. Follow-up of each participant will require another 6 months. Therefore, the total time required between the first visit of the first participant included and the last visit of the last participant is approximately 12 months. Description of the Experimental Intervention: The COVID-19 Vaccine (mRNA) - Bio-Manguinhos/Fiocruz is a monovalent vaccine for the prevention of severe cases of COVID-19. The product under investigation consists of a formulation containing messenger ribonucleic acid (mRNA) encoding the Spike protein of the XBB variant of the SARS-CoV-2 virus. Randomization: There will be no randomization in this study. Blinding/Breaking of Blinding: The study is open-label. There will be no blinding.