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Moderna gets OK for second phase of testing on coronavirus vaccine

If all goes well, final testing could begin this summer, Cambridge biotech says

Laboratory equipment at Moderna's headquarters in Cambridge.Adam Glanzman/Bloomberg

The Cambridge biotech Moderna said Thursday that it has gotten approval to start the second phase of a clinical trial of its potential vaccine for COVID-19 and that it hopes to begin testing it on 600 volunteers shortly.

If the vaccine is safe and effective ― big ifs in the world of biopharma, where most experimental drugs and vaccines ultimately never win approval ― Moderna plans to begin testing it in the third and final phase of clinical trials early this summer. The company had previously predicted the final phase would start in the fall.

“The imminent Phase 2 study start is a crucial step forward as we continue to advance the clinical development of mRNA-1273, our vaccine candidate against SARS-CoV-2," Moderna’s chief executive, Stephane Bancel, said of the virus that causes COVID-19.


Moderna was the first drug company to enter clinical trials with a potential vaccine, which researchers began injecting into the shoulders of healthy volunteers on March 16 in Seattle. There are at least 123 vaccine candidates around the world, according to the Milken Institute, an economic think tank in Santa Monica, Calif.

Most public health experts predict it will be at least 12 to 18 months before any vaccine could be deployed, and some say that’s naively optimistic. Many vaccine makers say they hope a number of candidates move forward into late-stage trials because it’s so challenging to develop a successful formula.

Shares of Moderna, which has no approved products, rose by more than 16 percent in premarket trading after the company announced the Food and Drug Administration had cleared its vaccine for the mid-stage trial. The stock closed at $53.19 Thursday, up 8.7 percent.

Moderna’s potential vaccine relies on custom-built messenger RNA to produce an immune response. The drug giant Pfizer said Tuesday that it had begun giving participants a rival experimental mRNA vaccine it’s developing with the German biotech firm BioNTech. No mRNA vaccine has ever won FDA approval.


Alan Carr, an analyst at Needham & Co., said the speed with which the clinical trials of the Moderna product have progressed is “very impressive.” But he said it was too soon to gauge the vaccine’s prospects of success until data about the immune response of volunteers become available. He hoped that would happen in the next couple of months.

Jonathan Saltzman can be reached at