The US Centers for Disease Control and Prevention (CDC) is grappling with an unprecedented loss of expertise following significant resignations and layoffs, coinciding with a decline in public trust as top health leaders diminish the importance of vaccines and other critical health tools.

“This should be concerning for Americans,” stated Nirav Shah, former principal deputy director at CDC and currently a visiting professor at Colby College. “These developments compromise our safety, especially as public health threats are on the rise.”

Project 2025, a conservative plan for a potential second Trump administration, aims to remove the CDC’s capability to provide guidance on vaccines and eliminate mandatory testing for new pathogens.

Experts warn that these alterations will impact US health for many years and further erode the public’s trust in health officials, which is already fragile.

“The loss of top, skilled experts leading vital units within the CDC threatens everyone’s safety,” warned Dorit Reiss, a law professor at UC Hastings College of Law.

The exit of four senior officials – Debra Houry, Demetre Daskalakis, Daniel Jernigan, and Jennifer Layden – has seriously impacted the nation’s health preparedness, according to Shah.

They joined thousands of health agency employees who have been laid off or resigned, with entire departments gutted, since Donald Trump was re-elected.

“Next time there’s a problem, we will not have qualified leadership for our response,” Reiss said.

The loss of “experienced, world-class” experts at the CDC is “directly related to the failed leadership of extremists” in charge of the Department of Health and Human Services (HHS), said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

The losses may continue under budget cuts, with proposed reductions of $5bn – a 42% decrease from 2024.

Two of the recently ousted officials will testify before Congress on Wednesday. Susan Monarez, the most recent CDC director, who was fired after 28 days, criticized the administration’s “reckless” approach to science, including a request to “rubber-stamp” recommendations from the CDC’s independent advisers.

The advisory committee on immunization practices (ACIP) plans to meet on Thursday and Friday. Advisers have indicated the committee will re-examine recommendations on routine childhood vaccinations such as those against hepatitis B and HPV (human papillomavirus).

The Make Our Children Healthy Again Strategy released on Tuesday “reaffirms that Kennedy is gunning for childhood vaccines”, Reiss said.

Emily Hilliard, an HHS spokesperson, said: “Secretary Kennedy has been clear: the CDC has been broken for a long time. Restoring it as the world’s most trusted guardian of public health will take sustained reform and more personnel changes.”

When asked about Kennedy’s stance on childhood vaccines, Hilliard said that HHS is “reaffirming the importance of the doctor-patient relationship so people can make informed decisions about their health”, emphasizing the roles of “clear, honest information and personal choice”.

Kennedy has also limited access to the Covid vaccines, restricting them only to people “at higher risk”, while also saying “anyone can get the booster”.

“Kennedy’s claim that anyone can get them is deeply insincere,” Reiss said. He already removed, for example, the recommendation for pregnant people, making it harder for them to access the vaccine.

“While it’s legal to give vaccines off-label, not all doctors and pharmacists will, and depending what ACIP does, not all insurers will cover them”, including Medicaid, which is bound by ACIP recommendations, she said.

Kennedy has repeatedly undermined the CDC and vaccines, calling the agency a “cesspool of corruption” and the Covid vaccine, for instance, the “deadliest vaccine ever made”. During the worst measles outbreak in decades, Kennedy framed vaccination as a personal choice. He has also cut millions of dollars for research on mRNA vaccines.

Earlier this month, Trump defended the Covid and polio vaccines. But the president has given Kennedy sweeping control over the nation’s health and nutrition agenda.

“In an era of rising threats to public health – whether it’s measles, whether it’s an Ebola outbreak, or whether it’s the continuing concern and threat from H5 [bird flu] – none of these things makes America healthy again,” Shah said.

The acting director of the CDC, Jim O’Neill, has a background in biotechnology investing but he does not appear to have training in medicine or public health.

“Based on what I understand, he does not have the requisite background to even be serving as acting director,” said Shah, who was acting director of the CDC while the Trump administration entered office.

“Americans need to ask themselves: ‘Are we safe right now?’” Shah said. “‘Is there somebody who knows at the higher levels what should be done in the face of an emerging Ebola outbreak? Are they doing it? How do we know that?’”

The news that top experts at the CDC haven’t briefed Kennedy is “alarming”, Shah said. ”If America’s top generals were planning a war and sketching out battlefield plans but had not talked to any of their lieutenants and colonels in the field, we would say that’s not leadership.”

So far, many Americans have not yet felt the shock waves of Kennedy’s changes to public health, Shah said.

For most people, “you don’t actually see the consequences of it until there’s an emergency”, Shah said. “And it’s way too late at that point.”