U.S. Health Secretary Robert F. Kennedy Jr. announced plans Tuesday to cancel $500 million in vaccine development projects.

In a statement from his office, the longtime vaccine critic said all projects to be halted use mRNA technology.

“After reviewing the science and consulting top experts at NIH and FDA, HHS has determined that mRNA technology poses more risk than benefits for these respiratory viruses,” Kennedy said in a video posted on social platform X, referring to Covid-19 and flu mRNA vaccines. The secretary has long been suspicious of the mRNA vaccine platform.

The planned cancellation of contracts includes work with Emory University and Tiba Biotech. Proposals from Pfizer, Sanofi Pasteur, CSL Seqirus, Gritstone and others will also be rejected, according to HHS.

Rick Bright, who led HHS’s Biomedical Advanced Research and Development Authority, or BARDA, from 2016 to 2020 — and criticized the Trump administration’s early Covid response — slammed the decision, calling it a “huge strategic misstep.”

“This decision signals a dangerous complacency,” Bright said in a text. “Disinvesting from mRNA strips us of one of the fastest tools we have to contain the next pandemic, natural or deliberate. Pulling back from proven medical countermeasure platforms at a time of escalating global bio‑risks deeply compromises national security.”

HHS said the cancellations impact 22 projects worth nearly $500 million — however, some contracts in their final stage will be “allowed to run their course to preserve prior taxpayer investment.”

The federal health department said it is instructing the Global Health Investment Corporation — which helps manage BARDA’s technological investments — to cease mRNA-based equity investments. However, HHS said other mRNA technologies “within the department are not impacted by this announcement.”

HHS said future BARDA vaccine investments will focus on technologies such as whole-virus vaccines and other new immunization platforms.