Moderna’s COVID-19 Vaccine Shows Nearly 95% Effectiveness in Phase 3 Study

Moderna, Inc.’s (Cambridge, MA, USA) Phase 3 study of its COVID-19 vaccine candidate has met the statistical criteria with a vaccine efficacy of 94.5%.

The independent, National Institutes of Health (NIH)-appointed Data Safety Monitoring Board (DSMB) for the Phase 3 study of mRNA-1273, its vaccine candidate against COVID-19, has informed Moderna that the trial has met the statistical criteria pre-specified in the study protocol for efficacy, with a vaccine efficacy of 94.5%. The study, known as the COVE study, enrolled more than 30,000 participants in the US and is being conducted in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, and the Biomedical Advanced Research and Development Authority (BARDA), part of the Office of the Assistant Secretary for Preparedness and Response at the US Department of Health and Human Services.


The primary endpoint of the Phase 3 COVE study is based on the analysis of COVID-19 cases confirmed and adjudicated starting two weeks following the second dose of vaccine. This first interim analysis was based on 95 cases, of which 90 cases of COVID-19 were observed in the placebo group versus five cases observed in the mRNA-1273 group, resulting in a point estimate of vaccine efficacy of 94.5%. A secondary endpoint analyzed severe cases of COVID-19 and included 11 severe cases (as defined in the study protocol) in this first interim analysis. All 11 cases occurred in the placebo group and none in the mRNA-1273 vaccinated group. The 95 COVID-19 cases included 15 older adults (ages 65+) and 20 participants identifying as being from diverse communities

The interim analysis included a concurrent review of the available Phase 3 COVE study safety data by the DSMB, which did not report any significant safety concerns. A review of solicited adverse events indicated that the vaccine was generally well tolerated. The majority of adverse events were mild or moderate in severity. Grade 3 (severe) events greater than or equal to 2% in frequency after the first dose included injection site pain (2.7%), and after the second dose included fatigue (9.7%), myalgia (8.9%), arthralgia (5.2%), headache (4.5%), pain (4.1%) and erythema/redness at the injection site (2.0%). These solicited adverse events were generally short-lived. Preliminary analysis suggests a broadly consistent safety and efficacy profile across all evaluated subgroups. Based on the interim safety and efficacy data, Moderna intends to submit for an Emergency Use Authorization (EUA) with the US Food and Drug Administration (FDA) in the coming weeks and anticipates having the EUA informed by the final safety and efficacy data (with a median duration of at least two months). Moderna also plans to submit applications for authorizations to global regulatory agencies.

“This is a pivotal moment in the development of our COVID-19 vaccine candidate. Since early January, we have chased this virus with the intent to protect as many people around the world as possible. All along, we have known that each day matters. This positive interim analysis from our Phase 3 study has given us the first clinical validation that our vaccine can prevent COVID-19 disease, including severe disease,” said Stéphane Bancel, Chief Executive Officer of Moderna.

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