Nov. 16, 2020: Moderna Announces That Its mRNA COVID-19 Vaccine Was 94.5% Effective in Its Phase 3 Trial
On Monday, Nov. 16, 2020, a Cambridge, Massachusetts, biotech company that had never brought a product to market announced results that would change the pandemic's trajectory. Moderna said an early look at its Phase 3 trial showed its COVID-19 vaccine candidate, mRNA-1273, was 94.5% effective at preventing symptomatic disease. The figure arrived as case counts climbed across the United States and Europe.
The Interim Analysis
The trial, run with the National Institutes of Health, had enrolled about 30,000 volunteers across the United States. An independent data safety monitoring board conducted the first interim analysis once 95 participants had developed confirmed symptomatic COVID-19. Of those cases, 90 were in the placebo group and only five were in the group that received the vaccine. The board also counted 11 severe cases, and all 11 were in the placebo group. Moderna said the vaccine could be stored at standard refrigerator temperatures, 36 to 46 degrees Fahrenheit, for 30 days, and at minus 4 degrees for six months, a practical edge for distribution. The company's design work had begun in January 2020, shortly after the virus's genetic sequence was published. A technology long considered promising but unproven had gone from a computer file to a late-stage trial in under a year, which is a pace that vaccine development had never come close to matching.
The announcement came one week after Pfizer and BioNTech had reported that their own mRNA vaccine was more than 90% effective, so Moderna's result served as confirmation as much as surprise. Two different companies, using the same underlying idea, had arrived at results far above the 50% efficacy that regulators had set as a minimum bar. Moderna cautioned that the data were preliminary and still needed review by regulators. That review came quickly. The U.S. Food and Drug Administration granted emergency use authorization to the vaccine on Dec. 18, 2020. For a company that had spent a decade as a scientific curiosity, a single Monday press release had been enough to turn years of skepticism about messenger RNA into one of the most closely watched medical results of the century.
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