AMNA NAWAZ: There are now more than 120 confirmed measles cases linked to an outbreak in Western Texas, the largest such outbreak the state has seen in over 30 years.

There are another nine cases further west in New Mexico.

GEOFF BENNETT: And that's raising questions about vaccine hesitancy in some communities and the growing challenge of these periodic outbreaks.

William Brangham has our look.

WILLIAM BRANGHAM: Unvaccinated people account for almost all these cases, and children are among the most affected.

We spoke with Dr. Ron Cook, who's a leading physician in Lubbock, Texas, who is trying to educate the community about this outbreak and the risks.

DR. RON COOK, Texas Tech University: If you walk into a room and you have measles, 80 to 90 percent of those individuals within a week will come down with measles.

All you have to do is go in that room, breathe, cough a couple of times, but 80 to 90 percent of those individuals in that room will become infected with measles if they're not vaccinated.

I have a granddaughter that's 10 months old, and I'm concerned about her potentially catching the measles virus and becoming very sick.

And there's -- some people would say it's just a virus, but, listen, it can cause significant hospitalizations.

It can cause encephalitis.

It can cause even death.

WILLIAM BRANGHAM: Dr. Cook also said the outbreak is particularly difficult to deal with because it's in such a rural area.

DR. RON COOK: We have to spend an inordinate amount of time trying to get what we call contact tracing.

We spend a lot of man hours trying to reach out and find people and who was there and what's their phone number and how do we get in touch with them.

WILLIAM BRANGHAM: Joining me now to discuss this outbreak and other issues concerning vaccines is Caitlin Rivers.

She's senior scholar at the Johns Hopkins Center for Health Security and author of ""Crisis Averted: The Hidden Science of Fighting Outbreaks."

Caitlin Rivers, so good to have you back on the "News Hour."

So this outbreak is in a rural part of Texas in an area with fairly low vaccination rates.

This is now the third such outbreak this year.

How concerning is this to you?

CAITLIN RIVERS, Senior Scholar, Johns Hopkins Center for Health Security: It is a concerning outbreak because of the logistical challenges you mentioned.

Moreover, measles is one of the most contagious viruses known to humanity, and so it's very difficult to control.

And so I do expect we will see more cases in the weeks ahead, but really hope that health officials are able to bring it under control sooner, rather than later.

WILLIAM BRANGHAM: And are we seeing more of these kinds of outbreaks?

And if so, what do you attribute this to?

Is this basically just more people are hesitant to take the vaccine, ergo, we see more measles?

CAITLIN RIVERS: Last year, 2024 was a fairly active year for measles.

We had a number of outbreaks around the country, mostly in people who are unvaccinated.

So that is the population we worry about most.

But I really encourage people to think twice about the talking points or the discussion that we often hear that implies that vaccinations are controversial.

In fact, 93 percent of people are vaccinated against measles.

That is an enormous congruency in a population that otherwise can't agree on a whole lot.

And so vaccines are actually incredibly popular.

And I think that is part of the messaging that can make parents who are considering vaccination feel more comfortable.

WILLIAM BRANGHAM: I hear exactly what you're saying about the popularity of vaccines, but we do know that skepticism is on the rise.

We spoke to one pediatrician in Brooklyn, New York, who described the process of having a lot of -- increasing numbers of parents who are resistant to taking the vaccines and what she has to do to hear them and try to persuade them.

Let's hear.

DR. TRICIA JEAN GOLD, Tribeca Pediatrics: I have to do these after-hours on the phone, after dinner.

I cannot do these during my day because how can I take care of children when you're on the front line and when they're sick?

So I have to have parents either come back so that we can give them the appropriate time they need for this in a completely separate visit.

Now, think about what that's doing also to health care for us.

We're already struggling to try and see the patients that we have and we're adding this in because of the doubt that's been placed upon the safety and efficacy of vaccines.

WILLIAM BRANGHAM: What do you make of that?

CAITLIN RIVERS: It is troubling to hear that parents are questioning vaccines.

And we know that the new secretary of Health and Human Services, Robert F. Kennedy Jr., has expressed doubt or skepticism about vaccines in the past.

And that does make me concerned about what's coming down the pipe.

But, again, what I also hear in that clip is that parents are willing to have the discussion.

They are curious.

They are open, even if they are coming from a place of skepticism.

And so I think it's important that we continue to reinforce that vaccines are popular, the vast majority of people get them.

And maybe, with some discussions and encouragement, those parents who are starting from a place of skepticism will be open to vaccination as well.

WILLIAM BRANGHAM: And how do you counsel pediatricians like the one we just heard from to have that conversation?

I mean, the point you make, I take it very clearly, that people overwhelmingly do support vaccination and believe in them.

But how do we talk about and to the skeptics amongst us?

CAITLIN RIVERS: Yes, I think having those conversations is so important, really listening to people's concerns and speaking to them.

It's difficult to do that at scale, and I have great sympathy for busy providers who are seeing patients in the clinic day in and day out struggling to fit in those conversations.

But we see over and over again that pediatricians and medical providers are among the most trusted messengers.

So I think it's important to make space for those conversations.

We also see public health officials continue to be trusted messengers, despite some reductions in trust that came out of the pandemic.

They're still overwhelmingly looked to as sources of trust.

Employers -- I think there are a lot of different kind of people who can be having these conversations and answering questions and really stepping in to make vaccination continue to be a stronghold or a strength of our public health system.

WILLIAM BRANGHAM: If people who have been vaccinated for measles perhaps long ago as a child, and they are seeing these stories about measles growing, should those people get re-vaccinated?

Is that a - - is there an update that people ought to take?

CAITLIN RIVERS: Two doses of the measles vaccine provides very good, durable protection.

And so that's not something I'm considering for myself or my family.

But if a member of the health department reaches out to you to let that you or a member of your family has been exposed to the measles virus, that's a question you can ask them and get individualized advice.

WILLIAM BRANGHAM: All right, Caitlin Rivers of the Johns Hopkins Center for Health Security, thank you so much for being here.

CAITLIN RIVERS: Thank you.