FDA review clears path for second coronavirus vaccine, this one by Cambridge-based Moderna

Trials showed the two-shot Moderna regimen was particularly effective against severe COVID-19 disease.

The headquarters of Moderna in Cambridge. Cody O'Loughlin / The New York Times

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By the end of the week, the United States could have two coronavirus vaccines.

A vaccine candidate developed by Cambridge-based biotechnology company Moderna appears poised for regulatory clearance after a detailed data review by Food and Drug Administration scientists confirmed the two-shot regimen was 94% effective in a clinical trial and carried no serious safety concerns.

The 54-page document positions the Moderna vaccine to follow the same historic track as the Pfizer-BioNTech vaccine. After the FDA gave a positive review of the Pfizer-BioNTech vaccine exactly a week ago, the shots were endorsed by a panel of outside experts on Thursday and granted a green light by regulators a day later. The first doses were administered to health care workers on Monday.


Much the same timeline is anticipated this week, given the similar results from Moderna’s vaccine and the fact that it relies on the same underlying technology.

Moderna’s vaccine will be reviewed Thursday by the same panel of independent experts at an all-day public meeting. The data they will consider echoes the evidence that led to a 17 to 4 vote to authorize the Pfizer-BioNTech vaccine, which was 95% effective. In addition, the two-shot Moderna regimen was particularly effective against severe disease. There were 30 cases of severe COVID-19, the disease caused by the virus, in the trial, none of them in the group that got the vaccine.

The Moderna vaccine worked well, regardless of age, race and gender. The adverse events associated were widespread, but short-lived, including fatigue, muscle aches and pain at the injection site.

In anticipation of its clearance, Gen. Gustave Perna, chief operating officer of the federal effort to develop and distribute vaccines, said Monday that the U.S. was preparing to ship almost 6 million doses of the Moderna vaccines to 3,285 locations in the first week.

“It will be a very similar cadence that was executed this week with Pfizer,” Perna said, “where we’re hitting initial sites on Monday, follow on Tuesday and Wednesday.”


The FDA reviews of both the Pfizer-BioNTech and Moderna vaccines cement the success of a new genetic vaccine technology, which could be used to rapidly create vaccines for other diseases.

Older vaccines work by injecting dead or weakened virus to teach the immune system to recognize the real pathogen. In contrast, the messenger RNA technology at the core of the Moderna and Pfizer-BioNTech vaccines delivers a strip of genetic material called RNA, encased in a fat bubble, to a person’s cells.

Once inside a cell, the messenger RNA co-opts the machinery used to make proteins to build tiny replicas of the spike protein that studs the outside of the coronavirus. The immune system learns to recognize – and block – the spike.

In Moderna’s trial, 30,000 people were randomly assigned to receive either two shots of a vaccine given four weeks apart, or two saline shots. Neither the participants, nor the people running the trial knew who was in which group. Investigators then waited as people were exposed to coronavirus in their daily lives, to see if there were more COVID-19 infections in the group that did not receive the real vaccine.

The numbers were decisive: There were 196 cases in the trial, all but 11 of them in the group that received the placebo shots. There were 30 cases of severe COVID-19, and one death from COVID-19 in the trial, also all in the group that received the placebo shots.


Enrollment in Moderna’s trial was slowed down this summer because scientists were concerned it lacked sufficient racial diversity to determine whether it truly protected those at highest risk of the disease. In the end, a fifth of participants were Hispanic, 10% were Black and four percent were Asian. More than 40% of the participants were either over the age of 65 or had medical conditions that increased their risk of severe disease.

“The trial enrolled the right people at risk,” said Larry Corey, a virologist at the Fred Hutchinson Cancer Research Center who co-leads the government’s clinical trial network responsible for testing coronavirus vaccines. “For us who were designing the trial and enrolling the people, that’s so fantastic.”



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