Safety and Immunogenicity Study of 2019-nCoV Vaccine (mRNA-1273) for Prophylaxis of SARS-CoV-2 Infection (COVID-19)

This is a phase I, open-label, dose-ranging clinical trial in males and non-pregnant females, starting at 18 years of age, inclusive, who are in good health and meet all eligibility criteria. This clinical trial is designed to assess the safety, reactogenicity and immunogenicity of mRNA-1273 manufactured by ModernaTX, Inc. mRNA-1273 is a novel lipid nanoparticle (LNP)-encapsulated mRNA-based vaccine that encodes for a full-length, prefusion stabilized spike (S) protein of SARS-CoV-2. Enrollment will occur at up to 3 domestic clinical research sites. Up to one hundred and fifty-five subjects will be enrolled into one of thirteen cohorts (10 micrograms \[mcg\], 25 mcg, 50 mcg, 100 mcg, or 250 mcg). Subjects will receive an intramuscular (IM) injection (0.5 milliliters \[mL\]) of mRNA-1273 on Days 1 and 29 in the deltoid muscle and will be followed through 12 months post second vaccination (Day 394). Follow-up visits will occur 1, 2, and 4 weeks post each vaccination (Days 8, 15, 29, 36, 43, and 57), as well as 3, 6, and 12 months post second vaccination (Days 119, 209, and 394). The primary objective is to evaluate the safety and reactogenicity of a 2-dose vaccination schedule of mRNA-1273, given 28 days apart, across 5 dosages in healthy adults. The secondary objective is to evaluate the immunogenicity as measured by Immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) to the SARS-CoV-2 S (spike) protein following a 2-dose vaccination schedule of mRNA-1273 at Day 57. Optional Substudy: This is an optional third mRNA-1273 vaccination substudy, in subjects 18 years of age and older, who received both the first and second mRNA-1273 vaccinations in the main study and meet all other substudy eligibility criteria. This optional third mRNA-1273 vaccination substudy is designed to assess safety, reactogenicity, and immunogenicity through 12 months post third vaccination (Day 731). Subjects who receive the third mRNA-1273 vaccination will exit the Schedule of Activities for the main study and will enter the Schedule of Activities for the optional substudy. Up to one hundred and twenty subject will be enrolled into two cohorts (consisting of participating subjects who received 2 doses of 25 or 50 mcg and participating subjects who received 2 doses of 100 and 250 mcg). Subjects will receive an IM injection (0.5 mL) at a dosage of 100 mcg/0.5 mL. The primary objective is to evaluate the safety and reactogenicity of a third mRNA-1273 vaccination, at a dosage of 100 mcg. The secondary objective is to evaluate the immunogenicity as measured by IgG ELISA to the SARS-CoV-2 S protein following a third mRNA-1273 vaccination, at a dosage of 100 mcg, at all timepoints after the third mRNA-1273 vaccination.