Shionogi & Co., Ltd. announced that Shionogi has initiated a Japanese Phase 2/3 clinical trial of a prophylactic vaccine candidate for COVID-19 (code No. S-268019), caused by the novel coronavirus (SARS-CoV-2) infection on October 20. This vaccine candidate is a new formulation with a modified adjuvant, and a Japanese Phase 1/2 clinical trial started in August 2021. In this trial, tolerability, safety and immunogenicity were evaluated in 60 Japanese adults, and the tolerability of this vaccine has been confirmed so far, and no major safety issues have been identified. Furthermore, the company confirmed a highly increased neutralizing antibody titer in subjects receiving this vaccine candidate. The company then initiated the Japanese Phase 2/3 clinical trial. The Phase 2/3 clinical trial that began in October (jRCT No.: 2031210383) is a open-label study. The safety and immunogenicity of two doses of the vaccine will be assessed and then they will confirm clinical benefit. In parallel with this clinical trial, they will prepare for the implementation of multiple clinical trials globally.We will continue to consult closely with the Ministry of Health, Labor and Welfare, Pharmaceuticals and Medical Devices Agency (PMDA) and other organizations regarding the design and implementation of these large-scale trials and regarding application for approval.