Moderna Completes Enrollment for Phase 2 Study of mRNA COVID-19 Vaccine

Moderna, Inc. (Cambridge, MA, USA) has completed enrollment for both cohorts of the Phase 2 study of its vaccine candidate (mRNA-1273) against COVID-19.

mRNA-1273 is an mRNA vaccine against COVID-19 encoding for a prefusion stabilized form of the Spike (S) protein, which was selected by the company for development. mRNA-1273 is Moderna’s second mRNA vaccine for an infectious disease to complete enrollment of a Phase 2 study, following the company’s CMV Phase 2 study, which was fully enrolled on March 3, 2020. The Phase 2 placebo-controlled, dose-confirmation study is evaluating the safety, reactogenicity and immunogenicity of two vaccinations of mRNA-1273 given 28 days apart. Each participant is receiving placebo, a 50 μg or a 100 μg dose at both vaccinations.


On June 11, 13 days after the first participant was dosed, the company announced that the cohort of healthy younger adults ages 18-55 (n=300) and the sentinel group of older adults ages 55 years and above (n=50) in the Phase 2 study of mRNA-1273 was complete. After reviewing the safety data from the sentinel cohort of older adults, on June 25, the Data and Safety Monitoring Committee of the study recommended Moderna to proceed with enrollment for the remainder of the Phase 2 study. The cohort of older adults (n=300) has now been fully enrolled. The company also announced that the cohorts of older adults (ages 56-70, n=30) and elderly adults (ages 71 and above, n=30) in NIH-led Phase 1 study have completed enrollment.

Additionally, Moderna has finalized the Phase 3 study protocol based on feedback from the US Food and Drug Administration (FDA). The randomized, 1:1 placebo-controlled trial is expected to include approximately 30,000 participants at the 100 µg dose level in the US and is expected to be conducted in collaboration with NIAID, subject to regulatory approval. Moderna has completed manufacture of vaccine required to start the Phase 3 study. With the Phase 3 dose at 100 μg, the company remains on track to be able to deliver approximately 500 million doses per year, and possibly up to one billion doses per year, beginning in 2021.

“I would like to thank the healthy volunteer participants, our partners at clinical trial sites and the dedicated Moderna team for their support in completing enrollment of the Phase 2 study of mRNA-1273, our vaccine candidate against COVID-19,” said Tal Zaks, M.D., Ph.D., Chief Medical Officer at Moderna. “We are committed to helping address this ongoing public health emergency and continue to focus on our Phase 3 study, which remains on track to start in July, less than seven months from the sequencing of the virus.”

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