Rachel Feltman: For Scientific American’s Science Quickly, I’m Rachel Feltman.
More than 1,000 cases of measles have been confirmed in the U.S. since late January, including a cluster in West Texas that has caused one of the worst outbreaks in recent memory. These outbreaks are occurring even though measles was technically eliminated in the U.S. back in 2000. Here to explain what that means—and why that status could be at risk—is Lauren Young, associate editor for health and medicine at Scientific American.
Lauren, thanks so much for coming on to chat with us today.
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Lauren Young: No, thank you for having me.
Feltman: So to refresh our listeners’ memories could you give us a brief overview of the current measles outbreaks of concern?
Young: Sure, so the situation continues to worsen in the U.S.; measles cases are continuing to rise. The current case count as of May 1 of the [Centers for Disease Control and Prevention’s] report says 935 confirmed cases, which is growing at a pretty alarming rate. The initial outbreak began in West Texas, and now it’s in 29 states, and we’re also seeing cases and outbreak spread in Mexico and Canada.
So it’s important to note, too, that nearly 70 percent of the confirmed cases [in the U.S.] have been in younger people, ages 19 and below, and a large proportion of those cases are in unvaccinated people …
Feltman: Mm.
Young: Which—and this is a concern ’cause measles is very highly contagious. It’s known for, you know, spreading via cough. It’s also known for creating a rash, which is pretty uncomfortable, coughing and runny nose, but it could also cause severe complications: it could open up people to pneumonia, organ failure and death. There’ve been three people who’ve died so far from these outbreaks, one adult and two children, and all three have been unvaccinated …
Feltman: Mm.
Young: So it’s definitely concerning. I know a lot of public health experts are keeping an eye on this and trying to understand, too, the public health response that’s going on.
Feltman: Sure, and just how abnormal is this compared to recent years?
Young: Right, so every year we do see cases of measles, and this often happens primarily due to travel—so when someone goes abroad to a place where measles is more common, they’ll come back and reintroduce, you know, some cases. But they’re usually relatively contained. What we’re seeing now is the highest number of cases since 2019, when we had a pretty large outbreak that started in New York.
But, you know, experts are pretty much in agreement that the case counts right now probably are also underestimations. When these cases started in West Texas, for instance, it was highly concentrated in Gaines County, which is known to have a pretty high population of homeschool children. And so it’s hard to understand fully the vaccination rates in kids, since, again, these outbreaks and the, the cases are highly concentrated in children, so yeah, public health experts are definitely keeping an eye on this and are concerned about what’s gonna happen in the next few months, yeah.
Feltman: Yeah, I think a lot of folks get confused about the statement that we hear a lot lately that measles has been “eliminated” in the United States. Could you explain what that status means and how we got it?
Young: Sure, so a disease gets “elimination” status when its incidence is reduced to zero in a specific region for a set time frame. It’s a little bit of a jargony, like, public health status thing, but the CDC and the World Health Organization define the status for measles as a period of 12 months with zero endemic cases, so that means there needs to be no continuous transmission of the disease over a 12-month period of time—so you can’t link one case from another case.
The United States achieved its elimination status of measles in 2000, and we’ve been able to keep that status primarily through prevention measures, particularly through vaccination. And, as we know, the measles, mumps and rubella vaccination, which is how you get vaccinated for measles, is pretty highly effective and very safe.
Feltman: Yeah, do experts think that that elimination status is at risk right now?
Young: Yeah, so there were a few prominent experts in the field of vaccine science who spoke out about this recently. Peter Marks, who was a former [Food and Drug Administration] official and he’s a prominent vaccine expert,said he’s worried that we’re on the way to losing this status. Also Katherine Wells, who is the public health director in Texas, said in March during a news briefing that she’s anticipating that this outbreak could go a year long …
Feltman: Mm.
Young: So that would definitely be pushing into that 12-month window for achieving that elimination status.
Feltman: As you mentioned, this isn’t our first big outbreak since 2000, so what factors are coming together to put our elimination status at risk after, you know, 25 years of success?
Young: Yeah, so there’s a few things that seem to be, you know, folding into play based off of what I’m just hearing from the experts that I’ve talked to. One, for sure, is: we’ve been seeing kind of this steady decline in vaccination rates, specifically in kids but, you know, just nationally as well, ever since the pandemic. A big part of that was: during the pandemic itself a lot of children missed their well appointments, where they would get their routine vaccinations. We did see, you know, some increase from that, but there’s other things at play.
There’s been a lot of anti-vaccine rhetoric that’s been going on that’s causing some of that increase to stagnate slightly, and, you know, experts are really highly concerned. We also have, you know, some public health officials in office right now who have a history of endorsing anti-vaccine rhetoric and are also endorsing studies to reevaluate things like autism and vaccines and that connection there.
So there’s just this heightened concern around vaccines. And when we see things like a decline in vaccination rates it’s very important for a disease like measles because it is so highly contagious. And for something like measles we need to see, as some experts have explained to me, very highly uniform vaccine coverage—in other words, high “herd immunity,” which is basically the level of either natural immunity or vaccination immunity you need to have in order to stop the spread of disease. So for measles you need about a 95 percent vaccination rate, and any sort of, you know, even slight decline in that can cause these severe outbreaks.
So that’s what we’re seeing here, where, you know, we have a small pocketed community that had a lower vaccination rate and is, you know, spurring this particular outbreak. But we’re seeing that also, too, in other places in the country where there might be even just a small dip in vaccination and it causes a disease to spread. And measles is kind of, as some experts have said, canary in a coal mine for vaccine-preventable diseases because it is so highly contagious, but if we continue to see this overall decrease in vaccinations for things like, you know, other eliminated diseases—like polio, for instance—that’s also a little bit of concern for several experts.
We did a whole story about this—Tara Haelle, one of our contributors, did a really deep dive on what that exactly would look like. So this is on the forefront of a lot of people’s minds, just the general interplay between vaccine recommendations from public health officials and also how that’s playing out from, you know, past historical trends. It’s all kind of coalescing together.
Feltman: Yeah, what do public health experts think we can do to keep measles from becoming endemic again?
Young: It seems maybe like a little bit beating a dead horse, but getting vaccinated, you know, I think is still an important thing to do. Listening to trusted health practitioners about treatment. Being active about, you know, going to the hospital or going and getting treatment if you’re seeing any signs or symptoms—which, again, include the rash, coughing, and the runny nose and watery eyes.
Feltman: Lauren, thank you so much for coming on. Unfortunately, I’m sure this won’t be the last time we talked to you about measles, but we really appreciate it.
Young: No, thank you for having me.
Feltman: That’s all for today’s episode. If you haven’t already submitted your answers for the Science Quickly listener survey, go check it out at ScienceQuickly.com/survey. Your responses will help us steer the future of the show, and you might just win a fun prize for helping us out. We’ll be back on Friday.
Science Quickly is produced by me, Rachel Feltman, along with Fonda Mwangi, Kelso Harper, Naeem Amarsy and Jeff DelViscio. This episode was edited by Alex Sugiura. Shayna Posses and Aaron Shattuck fact-check our show. Our theme music was composed by Dominic Smith. Subscribe to Scientific American for more up-to-date and in-depth science news.
For Scientific American, this is Rachel Feltman. See you next time!
