EXCLUSIVE: Moderna has halted a trial of a new mRNA vaccine for young people after a suspected myocarditis case

The case, which occurred in a Phase 1 trial of Moderna's jab for the Epstein-Barr virus, will only add to the concerns around mRNA biotechnology and heart issues, particularly myocarditis.

Investigators for Moderna today halted an early-stage clinical trial for its mRNA Epstein-Barr virus vaccine in adolescents after a participant in the trial developed a suspected case of myocarditis.

The case “necessitates an immediate suspension of all dosing for ALL adolescents,” an investigator at the company that is supervising the trial for Moderna wrote, adding, “Please confirm understanding and receipt of this urgent communication.”

The trial subjects should continue to be monitored for safety, the investigator wrote. About 150 adolescents are in the trial, along with 272 people aged 18-30.

A person not employed by Moderna, which makes the Spikevax Covid vaccine, provided the email to Unreported Truths.

Moderna did not disclose the trial halt, which occurred before stock markets opened for trading Thursday, to investors. Moderna stock is down about 85 percent from its highs in 2021, as sales of Spikevax lag, but it remains among the most valuable biotechnology companies, with a $30 billion market value.

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(All Dosing Must Pause Immediately! A partial subject line from the email sent halting the trial. Note the email time stamp - before Moderna stock opened for trading Thursday.)

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The Epstein-Barr virus, which causes mononucleosis, is one of Moderna’s leading candidates for new vaccines. The company has told investors it could reach billions of dollars in sales a year.

But the trial halt raises questions for Moderna and mRNA jabs that go far beyond the Epstein-Barr vaccine - officially called mRNA-1189 - alone.

The vaccine uses essentially the same design as Moderna’s Covid shot. Both jabs include a strand of modified mRNA surrounded by a tiny fat globule called a “lipid nanoparticle,” or LNP.

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The mRNA Covid shot has been linked to a increased risk of myocarditis - an inflammation of the heart muscle that can cause cardiac arrest and death. The risk is highest in teenagers and young people.

Since the myocarditis risk for the Covid mRNA jabs emerged in 2021, scientists have struggled to find its root cause. Some have argued it is related to the coronavirus spike protein that the Covid mRNA jab causes the body to make.

But other researchers believe it results from a more fundamental problem with mRNA biotechnology, possibly the lipid nanoparticles, which are known to produce an inflammatory response.

The fact that a second, non-Covid mRNA vaccine has now been linked to a suspected case of myocarditis in an adolescent will fuel the concerns that mRNA biotechnology - at least with the current lipid nanoparticles available - is unsuitable for young people.

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(The full email. Note that “Part B of the protocol” refers to the 12-17 year-old participants, so the case must have occurred in one of them.)

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The Epstein-Barr virus that Moderna’s mRNA-1189 jab targets is widespread worldwide and a major cause of mononucleosis in adolescents. Though mono is generally mild and transient, Epstein-Barr has also been linked to lymphoma in adults, particularly in immune-compromised people.

Moderna is one of several companies pursuing an EBV vaccine, though progress has been slow because of the complexity of the virus. mRNA-1189 actually causes the body to make several pieces of the virus, rather than just one, as Moderna’s Covid jab does.

The trial halted today, called Eclipse, is a Phase 1 trial - the most basic stage of human testing. In Phase 1 trials, vaccines and drugs are primarily evaluated for their safety, rather than how well they work.

Moderna began the trial in January 2022, aiming to enroll 272 participants aged 18-30, then expanded it to “Part B” for adolescents. Anyone with a history of myocarditis was specifically excluded from participating.