By Josh Nathan-Kazis

Shares of the biotech Moderna were up on Wednesday, as the Trump administration's shifting position on messenger RNA-based vaccines and therapeutics appeared to tilt slightly in the company's favor.

Moderna, which developed one of the mRNA-based Covid-19 vaccines that was launched during the pandemic, has seen its stock price fall 70% over the past 12 months. The market for the shots has collapsed, and the company's outlook has dimmed.

Simmering antipathy from figures close to President Donald Trump toward mRNA technology, which underlies Moderna's products and pipeline, has weighed on the company's valuation. The administration's opposition to mRNA took a major public step forward last week, when Robert F. Kennedy Jr., the U.S. health secretary, announced that his agency's pandemic-preparedness division would stop funding development of messenger RNA-based vaccines.

Though the U.S. Department of Health and Human Services had already yanked a $600 million contract from Moderna in May to develop an mRNA-based avian flu vaccine, Kennedy's early August edict was an even bigger blow. Alongside the announcement, Kennedy posted a video on social media in which he alleged that mRNA-based vaccines "can actually prolong pandemics."

Moderna shares fell 2.8% on the day of the announcement, and continued to slide through Monday's close.

Kennedy's conclusion, though well outside of the scientific consensus, appeared to be the official position of the U.S. government. It seemed to cut off future use of mRNA-based vaccines by the federal agencies he controls.

That would have significantly negative implications for Moderna, which sold billions of dollars worth of its Covid-19 vaccine to the federal government. The company relies on the Food and Drug Administration to approve its pipeline of new medicines.

Late Tuesday, however, shortly before the close of the market, another senior Trump administration official offered a defense of Kennedy's policy that took a much softer line on mRNA. In an op-ed in the Washington Post, Dr. Jay Bhattacharya, director of the National Institutes of Health, argued that HHS was right to stop developing mRNA-based vaccines.

But Bhattacharya didn't dismiss the technology entirely. Instead, he wrote that mRNA is "promising technology," and that the reason to stop developing mRNA-based vaccines is how the public sees the technology, not its scientific promise.

"I do not dispute its potential," Bhattacharya wrote. "In the future, it may yet deliver breakthroughs in treating diseases such as cancer, and HHS is continuing to invest in ongoing research on applications in oncology and other complex diseases."

Bhattacharya's essay wasn't a love letter to mRNA, or to Moderna. He wrote that "mRNA technology has special biological features that make it different from other vaccines," and that "getting approval for a vaccine with such inherent uncertainties should be difficult."

Still, his essay seemed significantly different in tone and implications than the statement last week from Kennedy, Bhattacharya's boss.

That muddying of the waters leaves unclear where U.S. government policy on mRNA-based vaccines under Trump will eventually land. For now, though, it seems like better news for Moderna.

The stock was up 3.9% on Wednesday afternoon while the S&P 500 was 0.2% higher.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

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August 13, 2025 15:16 ET (19:16 GMT)

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