Measles continues to spread in the U.S. with South Carolina currently experiencing the biggest outbreak it's seen in decades.

In that state, there are 876 confirmed cases of the highly contagious virus, which is preventable with a vaccine.

This current surge may be slowing. New cases aren't rising as fast, and vaccinations have picked up.

But doctors warn there are still serious risks for vulnerable populations, including children

and pregnant women. For more, we are joined again by Caitlin Jettelina. She writes the excellent

newsletter called Your Local Epidemiologist.

Caitlin, thanks so much for being here.

How serious is this outbreak in South Carolina?

I mean, how would you compare it to past outbreaks? And how did it get this bad this quickly?

Yeah, this outbreak in South Carolina is bad and it is historically large.

Like you said, 876 cases.

And this is larger than any other recent landmark U.S. outbreak.

In 2025, the West Texas outbreak ended at 762 cases.

In New York City, the 2019 outbreak had 649 cases. So this is one of the largest

outbreaks in decades, and certainly the largest since the U.S. achieved measles elimination

in 2000. This is also concerning because of the timing. Measles is usually

quieter in January and February. It usually really picks up in the spring. And the reason this is

happening is the core driver is susceptibility. We have pockets and these pockets are getting larger and larger of low

vaccination rates. And given that measles is the most contagious virus in the world, it will find

those pockets. It's like a kindling. And once it gets caught, it can spread like wildfire.

And again, can you remind us why we really worry about

measles and why we want to keep it at bay? Well, measles is preventable. We have a highly

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