Daiichi Sankyo Company, Limited announced the progress of development of DS-5670, an mRNA vaccine in Japan, being evaluated against the novel coronavirus infectious disease (COVID-19), including results from a phase 1/2 clinical trial. The trial was initiated in March 2021 to evaluate the safety and immunogenicity 1 of DS-5670 and to estimate the recommended dose. No relevant safety concerns have been observed following four weeks of follow-up after administration of the second dose of the vaccine in 142 healthy adults, including elderly individuals. For the immunogenicity, both neutralizing activity 2 and IgG titer 3 increased after the vaccination. A non-clinical research project conducted in collaboration with the University of Tokyo's Institute of Medical Science showed that DS-5670 induced a neutralizing activity against previously designated Variant of Concerns, including the Delta variant. Daiichi Sankyo plans to initiate a phase 2 clinical trial in November 2021 and a phase 3 clinical trial within FY2021, aiming for commercialization of DS-5670 in Japan within 2022. In addition, in order to initiate a clinical trial of a supplemental booster for the vaccine (booster vaccine) in January 2022, Daiichi Sankyo is continuing discussions with the Japanese Ministry of Health, Labour and Welfare (MHLW), Pharmaceuticals and Medical Devices Agency (PMDA), and Japan Agency for Medical Research and Development (AMED). These R&D projects are being conducted through the "Development of vaccines for the novel coronavirus disease (COVID-19) (Second Round)" (company-initiated) promoted by AMED and "Emergent Initiative to Build Production Capacity for COVID-19 Vaccines (First Round)" supported by MHLW.