GEOFF BENNETT: President-elect Trump's decision to nominate Robert F. Kennedy Jr. as secretary of Health and Human Services is sparking concern and criticism in the world of public health.

That's due in part to Kennedy's long-held beliefs against vaccines.

There are worries, too, about his history of false statements and beliefs in debunked conspiracy theories on subjects like HIV and AIDS, antidepressants, and autism.

At the same time, he's pushing hard on some major problems that experts say are real, like nutrition, obesity, processed food among them.

We're joined now by Katelyn Jetelina, who works in public health and writes the Substack newsletter Your Local Epidemiologist.

Thanks for being with us.

KATELYN JETELINA, University of Texas Health Science Center: Thanks for having me.

GEOFF BENNETT: So we should say HHS is a sprawling bureaucracy, 80,000 employees across 13 agencies.

If RFK Jr. is confirmed, what would it mean for all of the things that HHS oversees, things like drug approvals, food safety, disease surveillance, in addition to Medicaid and Medicare?

KATELYN JETELINA: Yes, I mean, these are our agencies that protect the health of Americans, everything from, like you said in the introduction, nutrition, to vaccines, to our data to see how the national health is going, where we can make improvements, where we cannot,the supports to local and public health departments.

So it is a $3 trillion dollar budget.

It's a massive job.

And someone that has a lot of experience needs to be there.

GEOFF BENNETT: He is one of the most prominent anti-vaccine activists in the country.

As you have pointed out in your writing, it's really the states that help determine vaccine policy when it comes to things like school mandates or exemptions.

So help me understand what your worries are about his potential impact if he is confirmed.

KATELYN JETELINA: Yes, so that's right.

So vaccine policy, it's primarily governed by individual states, rather than the federal government.

However, there certainly are places there's levers, indirect levers where the federal government can indirectly influence vaccines.

So, for example, FDA, right?

RFK has repeatedly said he wants a more rigorous vaccine reviewer process, which signals something to the FDA process.

But given that the United States has one of the most rigorous review processes for vaccine safety and effectiveness, it's really unclear what he wants changed or what data would be considered sufficient.

But, nonetheless, more data or more review processes could delay new vaccines.

It just adds time.

And this is a problem, for example, during a pandemic or an emergency.

Also, the FDA could remove emergency use authorization, for example, for the next pandemic.

Then there's also CDC, right?

They recommend childhood routine vaccination schedules, and it's been long criticized by RFK Jr.

The problem is, if this recommendation changes, there's downstream effects, like insurance companies could stop covering them.

And adding cost could easily deter uptake.

And then, of course, there's other levers, like Trump has suggested using the Department of Education to withhold funds from schools that mandate vaccines.

But, honestly, my biggest concern isn't necessarily through all the policy itself, but it's the indirect lever of sowing doubt and confusion about vaccines from one of the most powerful offices.

It can make a profound impact on Americans' ability to make evidence-based decisions.

GEOFF BENNETT: There are Americans, though, who welcome a different approach when it comes to cracking down on processed foods, removing food chemicals and additives, which RFK Jr. says he wants to do.

And there was a new study published in "The Lancet" that found nearly three-quarters of American adults are overweight or obese, and RFK Jr. attributes some of that to what he sees as this corrupt alliance between the food and drug industries and the regulators that are supposed to act as a check on them.

What do you make of that?

KATELYN JETELINA: Yes, I think we can all agree that America has room for improvement, right?

We live the shortest lives, have the most avoidable deaths, have worse health outcomes compared to other developed countries.

The first step is accurately identifying what is causing us to be unhealthy and fix that.

I do think that there is need for improvement, for example, through the regulatory process and through a conflict of interest.

But a lot of the make America healthy again talking points are not necessarily -- are focusing on organic food or demonizing pesticides that just won't move the needle.

And, look, I think I'm going to agree with things RFK Jr. says.

He says reasonable statements, but then mixes them with outright falsehoods.

And in the end, I think it's a matter of whether RFK Jr.'s net impact is positive or negative.

And given his history of sowing doubt in incredibly effective public health interventions, he can do a lot of harm.

GEOFF BENNETT: I know from my own reporting how hard it is to make seismic changes at some of these agencies like NIH and FDA.

What's the worst-case scenario, if Kennedy is confirmed and makes good on his promise of transforming public health as we know it, combined with Donald Trump's promise to weaken civil service rules?

KATELYN JETELINA: Yes, look, I agree, CDC, FDA, they need improvements.

In fact, I have been working with CDC over the past three years for improvements.

However, it needs to be done very carefully, because our public health system in the United States is incredibly fragile.

For example, a lot of people don't realize that 90 percent of funding to local and state public health departments come directly from the CDC.

So say we cut, for example, the Center Injury, which is actually on the chopping block right now in the congressional budget.

That means states won't get funding for the opioid crisis, which means lack of education or resources.

And we just got that epidemic started to decrease again.

So I think that a lot of these cuts, they're going to have implications to the CDC institution, obviously, but there can be grave downstream impacts.

And we need to be very careful on how we do that.

And I just haven't seen a careful narrative that has taken that into place yet.

GEOFF BENNETT: How should some of these public health agencies be preparing, in your view?

KATELYN JETELINA: I think that it's what we're doing right now a lot on the ground is that we have to gain trust with the public, right?

That means we have to build bridges, instead of manning barricades.

That means finding common ground.

That means recognizing what we say and how matters, especially to people that are hesitant or believe in conspiracy theories, that anger and shame will only drive people further away.

And people, Americans need their answers - - their questions answered, right, not necessarily to be told what to believe.

And I think we all play a role in this, especially at the federal government, right now.

GEOFF BENNETT: Katelyn Jetelina, thanks so much for your insights.

We appreciate it.

KATELYN JETELINA: Thanks for having me.