Sen. Ron Johnson, R-Wis., ranking member of the Senate Homeland Security Permanent Subcommittee on Investigations, wrote a letter to the Department of Health and Human Services (HHS), Food and Drug Administration (FDA), and Centers for Disease Control and Prevention (CDC) demanding immediate preservation of "all records referring or relating to the development, safety, and efficacy of the COVID-19 vaccines."

Johnson's office said "these agencies have refused to provide complete and unredacted documents" in response to the senator's previous oversight letters.

“In addition to hiding relevant information from Congress, your agencies have applied heavy redactions to public documents released under Freedom of Information Act (FOIA) requests. These redactions have made many of these public documents hard to understand and, in countless instances, impossible to read,” the senator wrote in his letter.

"[W]hile your agencies have largely ignored or failed to fully cooperate with my oversight efforts, I can assure you that your obstruction will soon come to an end. In the next Congress, when I become chairman of the Permanent Subcommittee on Investigations, any attempt by your agencies to withhold documents will be met with a subpoena," he also wrote.

The senator requested HHS, FDA, and CDC produce certain documents without redactions by December 3, 2024, including a Pfizer report on "myocarditis and pericarditis" as well as CDC "communications contemplating whether to issue a health alert on myocarditis."