One hundred days ago, toward the end of August, I resigned from my position as chief medical officer of the Centers for Disease Control and Prevention (CDC) along with two colleagues. Our departure was prompted by our inability to remain silent as scientific integrity was undermined and the nation’s public health infrastructure was weakened under Robert F. Kennedy Jr., the Secretary of Health and Human Services (HHS). At that moment, we implored Congress, professional organizations, and public health stakeholders to intervene before irreversible harm occurred. I left feeling optimistic.

For several weeks after my resignation, the public paid attention. There was scrutiny regarding the misinformation emanating from the Secretary, the disarray in the response to a measles outbreak, the unprecedented dismissal of members from the Advisory Committee on Immunization Practices (ACIP), and troubling alterations in how the CDC communicates with the public.

This public attention culminated in a Senate HELP Committee hearing in September, where former CDC director Susan Monarez informed senators that she was pressured to endorse vaccine recommendations and dismiss experienced career scientists. I also testified about discovering changes to CDC guidance through tweets, the Secretary’s promotion of unproven treatments during a measles outbreak, and HHS leaders making data requests outside of established protocols.

But now, 100 days later, the situation has not improved. In fact, it has worsened. And Congress has still failed to take action.

Earlier this summer, the Senate appropriations committee expressed concern in its budget language regarding the ongoing hiring of political appointees at the CDC. HHS once again disregarded Congressional directives. Since September, the CDC has brought on board at least two more political hires, increasing the total to 14 political leaders and no career scientists in the Office of the Director. The interim CDC director, Jim O’Neill, is neither a scientist nor a physician. These most recent hires, Mark Blaxill and Dr. Ralph Abraham, have publicly expressed anti-vaccine sentiments.

In October, we observed additional terminations—though some were eventually reversed—of CDC staff, including those involved in the Ebola and measles responses. Furthermore, despite the Secretary’s repeated calls for “gold-standard science” and “radical transparency,” it remained unclear why the ethics office, the Institutional Review Board office, and the unit overseeing Federal Advisory Committees were targeted.

The CDC website has transitioned from a data-rich resource to pages reflecting political agendas. The content now includes negative references to immigration, abortion, gender ideology, and harm reduction. Data and science, not ideology, should form the foundation of the CDC. Mentions of “mpox” have been reverted to “monkeypox,” despite the WHO’s 2022 recommendation to use the former term to prevent stigmatization. And in November, CDC scientists discovered a revised page on autism and vaccine safety that misrepresented decades of research. Consequently, several health departments have now removed links to the CDC on their websites.

Sixteen strategic initiatives—developed and directed by political appointees without scientific or programmatic review—were introduced at a senior leadership meeting in November. Through a widely circulated PowerPoint presentation, I learned that some priorities, such as “enhancing scientific rigor,” are not being led by scientists but by two political appointees: an aviation attorney and a realtor who authored a self-published book on heaven.

The December ACIP meeting this week marked an unprecedented low. The three presenters discussing the hepatitis B vaccine were not vaccine scientists, and two had co-authored a book about autism. Additionally, the Secretary’s ally, Aaron Siri, an anti-vaccine trial lawyer who previously petitioned the FDA to revoke approval of the polio vaccine, was given a platform to present on the childhood vaccine schedule. We saw a precursor to this in September, when the newly constituted ACIP concentrated on hypothetical risks of vaccines while downplaying established benefits and voted to restrict recommendations for the MMRV and COVID vaccines. This has resulted in diminished access to those vaccines for specific populations.

The ramifications of the CDC’s new direction are not merely theoretical. They are evident in children’s hospital beds. We have observed an increase in pediatric deaths from vaccine-preventable diseases, including whooping cough. Measles outbreaks that should have been promptly contained have continued due to suppressed information about vaccine safety and delayed intervention. These are not shortcomings of clinicians or health departments. They are failures of federal leadership: predictable outcomes when trusted scientific voices are replaced by ideologically driven leaders. The nation’s public health infrastructure is being destabilized.

Vaccines have emerged as the most prominent point of contention, but the deeper crisis is whether the U.S. will retain a science-driven public health agency capable of safeguarding the nation. What we have witnessed at the CDC is not reform. It is the dismantling of an institution Americans rely on in every emergency. The actions taken since late summer will leave the country less prepared for the next measles outbreak, foodborne illness cluster, maternal mortality crisis, or emerging pandemic. These changes are occurring quietly, rapidly, and with almost no oversight.

When I resigned, I believed that bipartisan members of Congress would intervene. Some have privately voiced concerns in briefings with me. However, meaningful oversight has been absent. Congress possesses various tools: hearings, subpoenas, appropriations language, whistleblower protections, and statutory safeguards. But unused tools are wasted tools.

At the 100-day mark, we have sufficient data points to understand that this is not a series of isolated errors. It is a deliberate restructuring of the CDC away from evidence-based practices and toward ideology-driven governance. Today, I once again urge: Congress, governors, health systems, scientific societies, and the private sector must act. Not with mere statements, but with oversight, pressure, and protection for the career staff who continue to serve with integrity. Just as physicians must always do what is right for their patients, I hope national leaders will do what is right for their constituents and not solely what will secure re-election—and that professional organizations and institutions will speak out on behalf of the health of Americans, instead of remaining silent for fear of losing funding.

I did not resign to make a symbolic gesture. I resigned because remaining silent would have made me complicit. I spoke up because the stakes for children, communities, and our national preparedness are too high. What unfolds next will determine whether the damage becomes permanent.