Sanofi and Translate Bio initiate Phase 1/2 clinical trial of mRNA COVID-19 vaccine candidate Clinical trial to assess safety, immune response and reactogenicity, after preclinical data showed high neutralizing antibody levels Expected to enroll 415 participants; interim results expected in Q3 2021 In parallel, preclinical studies are underway to evaluate additional mRNA candidates against emerging SARS-CoV-2 variants PARIS and LEXINGTON, MASS. - March 12, 2021 - Sanofi Pasteur, the vaccines global business unit of Sanofi, and Translate Bio (NASDAQ: TBIO), a clinical-stage messenger RNA (mRNA) therapeutics company, today announced the start of the Phase 1/2 clinical trial for MRT5500, an mRNA vaccine candidate against SARS-CoV-2, the virus that causes COVID-19. The Companies expect interim results from this trial in the third quarter of 2021.