Moderna Coronavirus Vaccine Shows 'Promising' Safety and Immune Response Results in Published Phase 1 Study, But More Research Is Needed

By Jacqueline Howard and John Bonifield, CNN

(CNN) -- A Covid-19 vaccine developed by the biotechnology company Moderna in partnership with the National Institutes of Health has been found to induce immune responses in all of the volunteers who received it in a Phase 1 study.

These early results, published in the New England Journal of Medicine on Tuesday, showed that the vaccine worked to trigger an immune response with mild side effects -- fatigue, chills, headache, muscle pain, pain at the injection site -- becoming the first US vaccine candidate to publish results in a peer-reviewed medical journal

The vaccine is expected to begin later this month a large Phase 3 trial -- the final trial stage before regulators consider whether to make the vaccine available.

Moderna noted in a press release on Tuesday that, if all goes well in future studies, "the Company remains on track to be able to deliver approximately 500 million doses per year, and possibly up to 1 billion doses per year, beginning in 2021."

In the Phase 1 study, "the goal was to look at safety and then to look at immune responses," said Dr. Lisa Jackson, a senior investigator at Kaiser Permanente Washington Health Research Institute in Seattle who was involved in the study. Early data from the study previously was released in May.

"We thought the immune responses look promising, but we don't know whether the levels we're seeing would actually protect against infection. It's really hard to know that until you do the actual efficacy trial," she said. "So we're laying the groundwork for the trial that will provide those answers."

Moderna expects to start the company's largest study yet of its Covid-19 vaccine candidate mRNA-1237 on July 27, according to details released separately on Tuesday. It's expected to be the first in the United States to begin Phase 3 trials.

For now, the new study "provided information rapidly that could be used to determine what dose to go forward with Phase 2 and Phase 3 trials. That's a critically important decision to make and so having that information available so soon after the vaccine trial was initiated is pretty remarkable," Jackson said.

A Phase 1 study typically studies a small number of people and focuses on whether a vaccine is safe and elicits an immune response.

In Phase 2, the clinical study is expanded and the vaccine is given to people who have characteristics -- such as age and physical health -- similar to those for whom the new vaccine is intended, according to the US Centers for Disease Control and Prevention. In Phase 3, the vaccine is given to thousands of people and tested for efficacy and again for safety.

'We want to know whether the vaccine is safe and effective'

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A Covid-19 vaccine developed by the biotechnology company Moderna has been found to induce immune responses in all of the volunteers who received it in a Phase 1 study. The image shows Moderna headquarters on May 08, 2020 in Cambridge, Massachusetts.

The Phase 1 study included 45 healthy adults, ages 18 to 55, who received two vaccinations of the mRNA-1237 vaccine candidate 28 days apart. Some of the volunteers enrolled in the trial at Kaiser Permanente in Seattle and others at Emory University in Atlanta.