Kennedy said the Department of Health and Human Services would retire all 17 current members of the ACIP, citing what he called a "crisis of public trust."

U.S. Secretary of Health and Human Services Robert F. Kennedy Jr. testifies before the Senate Committee on Health, Education, Labor, and Pensions on Capitol Hill on May 20, 2025 in Washington, DC. (Photo by Tasos Katopodis/Getty Images)

Ramakrishnan M·Stocktwits

Updated Jul 02, 2025 | 8:31 PM GMT-04

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Several vaccine maker stocks slipped in after-hours trading Monday after Health Secretary Robert F. Kennedy Jr. announced a sweeping overhaul of the CDC's Advisory Committee for Immunization Practices (ACIP), sparking concerns among retail traders about the direction of vaccine policy in the United States.

After the closing bell, Pfizer shares dropped nearly 1.3%, while Moderna fell over 1%. BioNTech dipped 0.26%, and GlaxoSmithKline edged lower by 0.12%.

In a Wall Street Journal op-ed published Monday, Kennedy said the Department of Health and Human Services would retire all 17 current members of the ACIP, citing what he called a "crisis of public trust."

He argued that restoring confidence in vaccines and public health institutions required more than incremental changes.

"Vaccines have become a divisive issue… That is why, under my direction, HHS is putting the restoration of public trust above any pro- or antivaccine agenda," Kennedy wrote.

"A clean sweep is needed to re-establish public confidence in vaccine science."

Kennedy, a longtime critic of vaccine mandates, explained that without this move, the current Trump administration could not appoint a majority of new committee members until 2028.

The ACIP shakeup, he said, was a necessary first step in reshaping federal health guidance.

On Stocktwits, retail trader sentiment reflected growing unease.

Moderna's sentiment turned more 'bearish,' while BioNTech's slipped from 'bullish' to 'bearish.' GSK's sentiment dropped to 'bearish' from 'neutral,' and Pfizer's remained 'neutral.'

Novavax bucked the trend and rose in extended trading, but retail sentiment on the stock remained 'bearish.'

BNTX sentiment and message volume as of Jun 9.png — BNTX sentiment and message volume as of Jun 9. | source: Stocktwits

MRNA sentiment and message volume as of Jun 9.png — MRNA sentiment and message volume as of Jun 9. | source: Stocktwits

GSK sentiment and message volume as of Jun 9.png — GSK sentiment and message volume as of Jun 9. | source: Stocktwits

PFE sentiment and message volume as of Jun 9.png — PFE sentiment and message volume as of Jun 9. | source: Stocktwits

NVAX sentiment and message volume as of Jun 9.png — NVAX sentiment and message volume as of Jun 9. | source: Stocktwits

The advisor overhaul is the latest in a string of dramatic policy changes since Kennedy took office as HHS chief.

Under his leadership, the department has stopped recommending routine COVID-19 vaccines for healthy children and pregnant women and has canceled research programs to prevent future pandemics.

Retail traders now appear to be reassessing their positioning in vaccine stocks, unsure how far the policy pivot could go.

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