By Elsa Ohlen

Shares of major vaccine makers Moderna and Pfizer held steady even as U.S. health secretary Robert F. Kennedy Jr. abruptly fired all vaccine policy advisors to the Centers for Disease Control and Prevention late Monday.

While the news isn't great for vaccine manufacturers, it could have been worse.

Shares of pure vaccine play Moderna fell 0.3% in premarket trading Tuesday. Pfizer and Merck, which also make vaccines alongside other pharmaceutical products, fell 0.1% and 0.4%, respectively.

The muted stock reaction may be due to the lead-up to the announcement. RFK Jr's is widely known to be a vaccine skeptic, and related stocks have already taken a serious hit in the past year.

Moderna is down 80% in the last 12 months, Merck has fallen 40%, and Pfizer has dropped 14%. Merck and Pfizer are now trading at a forward price to earnings ratio of 8.6 and 7.9, respectively. Moderna has been making a loss in six out of the eight last quarters.

The overhaul to CDC's Advisory Committee on Immunization Practices (ACIP) is a risk to vaccine manufacturers, Leerink analysts led by Daina Graybosch said. "At best, it will take time for the new members to ramp up on the content and ACIP process," she said. "At worst, the committee could upend current recommendations for novel and existing vaccines."

The analysts see risks for all vaccine manufacturers following this decision, including for Merck, BioNTech, Pfizer, Sanofi, Moderna, GSK and Celestica.

Investors will also be waiting for news on how the makeup of a reconstituted ACIP will look like.

"New members will likely be sympathetic to at least some of RFK's beliefs regarding alleged dangers of vaccines," Graybosch said. "Since [Monday's] statement criticizes that the committee 'has never recommended against a vaccine,' it suggests that ACIP could be more critical of vaccines, which could negatively impact approved vaccine recommendations and increase the burden of evidence and costs for future vaccine development."

However, with ACIP remaining in place, this outcome is less disruptive than it could have been, with some having feared RFK Jr's appointment would lead to the committee being disbanded completely, William Blair analysts led by Myles Minter noted.

Write to Elsa Ohlen at elsa.ohlen@barrons.com

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June 10, 2025 08:18 ET (12:18 GMT)

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