A Senate investigative report released by Sen. Ron Johnson (R-Wis.), chairman of the Senate Permanent Subcommittee on Investigations, alleged that federal health officials were aware of reports of myocarditis and related cardiac inflammation following mRNA COVID-19 vaccination months before broader public warnings were issued, according to a press release from Sen. Johnson's office. The interim Majority Staff Report was released alongside more than 2,400 pages of records obtained from the Department of Health and Human Services following a January 2025 subpoena.
According to the report, federal agencies including the CDC and FDA received early reports from Israeli health officials in February 2021 describing myocarditis cases in young adults following administration of the Pfizer-BioNTech vaccine. Israeli health officials later reported 275 myocarditis cases identified between December 2020 and May 2021, including 148 cases occurring near the time of vaccination. Of those 148 cases, 121 occurred after a second vaccine dose. Most cases were reported in males aged 16 to 19 years, and 95% were described as mild. The cases were out of over 5 million vaccinated individuals.
The report also cited Vaccine Adverse Event Reporting System (VAERS) data reviewed by US officials during spring 2021. By June 11, 2021, CDC investigators had received 1,226 reports of myocarditis after mRNA COVID-19 vaccination, including 687 reports among individuals younger than 30 years. Among reports with sex available, 923 cases occurred in males. CDC reviewers determined that 323 cases met agency case definitions for myocarditis, pericarditis, or myopericarditis.
CDC data reviewed during a June 2021 Advisory Committee on Immunization Practices meeting showed myocarditis reporting rates of 40.6 cases per million second mRNA vaccine doses administered among males aged 12 to 29 years. The highest reported rates were among males aged 12 to 17 years and 18 to 24 years, at 62.8 and 50.5 cases per million second doses, respectively. Among the 323 confirmed CDC-reviewed cases, 96% of patients were hospitalized, although most clinical courses were described as mild and no deaths were reported in that review.
The report described internal discussions among federal officials regarding whether to issue formal communications to clinicians and the public. According to documents cited in the report, CDC officials drafted a warning for health care providers in May 2021 related to myocarditis and pericarditis after mRNA vaccination. The report alleged that concerns about causing alarm contributed to delays in broader public notification. Vaccine labeling changes and public advisories regarding myocarditis risk were issued in late June 2021.
The Senate report was released in conjunction with a hearing titled, “The Corruption of Science and Federal Health Agencies: How Health Officials Downplayed and Hid Myocarditis and Other Adverse Events Associated with the COVID-19 Vaccines.” The investigation remains ongoing, according to the subcommittee.
