Moderna's coronavirus vaccine just showed early signs of success in an early study in people (MRNA)

In a small number of healthy volunteers, Moderna's vaccine helped create immune responses that may help protect people from being infected with the novel coronavirus.
The biotech is planning to start additional trials immediately and is aiming to be ready this fall for potential emergency use of its vaccine.
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In a milestone moment in the race for a coronavirus vaccine, the first results in humans showed Moderna's vaccine candidate led to antibody responses in a handful of healthy volunteers.

The Massachusetts biotech described Monday the immune system responses to the vaccine from this first, small study that was primarily focused on safety. The results don't yet show whether the vaccine would prevent people from being infected with the novel coronavirus.

The trial was conducted by the US National Institutes of Health. Moderna is planning to soon start a mid-stage study and then begin a late-stage trial in July. The company is aiming to be ready for potential emergency use of its vaccine this fall, a timeline with no precedent in the history of vaccine development.

This trial enrolled 45 healthy volunteers to start, ages between 18 and 55 years old and randomly given one of three dose strengths for two shots: 25 micrograms, 100 micrograms and 250 micrograms.

All participants developed detectable antibodies, and Moderna said there were "dose dependent increases in immunogenicity" across the three potencies.

The 15 volunteers at the weakest dose strength also had antibodies in their blood at similar levels to people who recovered from COVID-19, after receiving both doses.

Follow-up data was more limited for the higher doses, as the volunteers are still being tracked. Ten people given both 100-microgram doses with sufficient follow-up had antibody levels that "exceeded the levels seen in convalescent sera."

Moderna also said they had data on neutralizing antibodies for eight people. All these volunteers showed neutralizing antibodies "at or above levels generally seen in convalescent sera."

The company also said the NIH has helped test the vaccine in mice. After being vaccinated, mice were exposed to the novel coronavirus. Moderna said the vaccine "prevented viral replication in the lungs" of these mice. Additionally, these early human data on levels of neutralizing antibodies were consisent with the mice data.

The vaccine was "generally safe and well tolerated," Moderna said. The company noted that at the highest dose level, 250 micrograms, three people have had severe but not life-threatening side effects. "All adverse events have been transient and self-resolving," the company noted, without further describing these side effects in the high-dose arm.

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