Why Childhood Vaccination Rates Are Falling

Tanya Lewis: Hi, this is Your Health, Quickly, a Scientific American podcast series!

Josh Fischman: We bring you the latest vital health news: Discoveries that affect your body and your mind.  

Lewis: And we break down the medical research to help you stay healthy. 

I’m Tanya Lewis.

Fischman: I’m Josh Fischman.

Lewis: We’re Scientific American’s senior health editors. 

Fischman: On today’s show, we’re going to talk about the alarming decline in vaccination rates for childhood illnesses like measles and polio, and what we should do about it—before there’s an outbreak.

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Lewis: COVID gave a huge boost to the antivax movement. But vaccination rates for many childhood diseases were starting to erode long before that.

Fischman: That’s right—it started with people like Jenny McCarthy and Robert F. Kennedy Jr. spreading false information about the effects of vaccines and autism, and got amplified from there. It’s really become an organized movement now.

Lewis: Absolutely. So it may not surprise you that during the pandemic, the number of kids getting routine vaccinations fell even more, leaving them more vulnerable to these diseases.

Fischman: That’s definitely not good. The last thing we need is another measles or whooping cough outbreak.

Lewis: Exactly. And some of these diseases can cause serious disability or even death—remember polio?

Fischman: My parents remember it vividly. Kids on crutches, horror stories of iron lungs, people fearing summer because that’s when cases peaked. And Jonas Salk became a huge hero because of his polio vaccine in the 1950s. 

Lewis: Right! It was a scary time. Thanks to vaccines, polio was nearly eradicated worldwide, except for Afghanistan and Pakistan. In August 2022, there was a case of polio in Rockland County, New York—the first U.S. polio case since 2013. The virus was also found circulating in wastewater.

Vaccination rates for polio in the Americas have dropped to about 80 percent—much lower than the 95 percent threshold public health officials say is needed.

Fischman: And it’s not just polio, right?

Lewis: Right—it’s also diseases like measles, mumps and rubella, or tetanus, diphtheria and pertussis. The Centers for Disease Control and Prevention just came out with a report saying that between 2019 and 2022, vaccination rates for many childhood diseases dropped from 95 percent to around 93 percent nationwide. Idaho had the lowest vaccination rate, at just over 81 percent. 

Fischman: A change from 95 to 93 percent doesn’t sound like a huge drop. But for diseases like measles, which are extremely contagious, its a big deal. Anything less than 95 percent could lead to an outbreak.

Lewis: Exactly. And we saw such outbreaks even before the pandemic. In 2019, there were more than 1,200 cases of measles across 31 states—the highest number since 1992. And most of the cases were in unvaccinated kids.

These trends only got worse during the pandemic. Measles cases increased by an estimated 18 percent worldwide, and deaths increased by 43 percent in 2022 compared with 2021, according to a recent report.

To find out why childhood vaccinations have declined, I talked to Jennifer Nuzzo.

Jennifer Nuzzo: I’m Jennifer Nuzzo. I’m the director of the pandemic center and professor of epidemiology at the Brown University School of Public Health.

Lewis: I asked her about the nationwide drop.

Nuzzo: Seeing it slip below 95 is deeply troubling. But the problem is actually probably greater than even that 93 percent statistic would suggest, because that’s sort of a nationwide average. You can still have pockets of the population where the coverage is actually quite low. And we have seen in the past, you know, where a state maybe has generally good vaccination coverage, but within a county, for instance, the coverage may be quite low and we’ve seen outbreaks occur in those circumstances. 

Fischman: So, what’s driving this drop in vaccination rates? Is it antivaxxers? Or is something more complex going on?

Nuzzo: I think we probably have a few things going on. And I think more work is definitely needed to figure out which among these things is driving this decline in coverage the most. But first of all, there were gaps in sort of preventative care that occurred during the pandemic and the coverage declines for MMR we don’t see across all age groups, and it suggests that perhaps some kids are still getting caught up.

Fischman: So basically, kids got behind on their shots because they weren’t going to the doctor as much, or didn’t have access to medical care?

Lewis: Right, that’s definitely part of it.

Nuzzo: I’m also mindful of the fact that we do see a difference in coverage according to insurance status, and according to different patient demographics, which may suggest that there are just gaps in provider coverage or not sufficient abilities to access vaccines in certain places.

Lewis: Nuzzo pointed out that it’s still a challenge for parents to get their kids vaccinated in general.

Nuzzo: It just still feels too hard. I mean, it seems unacceptable for me that parents have to take off of work in order to make sure they can get to an appointment that’s, you know, frustratingly scheduled in the middle of the day, etc. That’s just not necessarily things that all parents can just easily do. So we need to make it easier for parents to get their kids vaccinated.

Lewis: But vaccine hesitancy and misinformation have clearly also played a role.

Nuzzo: I do think that there has been an unfortunate attack on vaccines, and perhaps a growing share of the American public questioning the value and safety of vaccines now as a result of the pandemic, and a lot of the mis- and disinformation that circulated around. 

Lewis: Every U.S. state has a mandate requiring kids be vaccinated in order to attend school.

Fischman: There are exceptions, though. Sometimes for medical reasons. But in recent years, more parents have gotten vaccine exemptions for their kids on religious or philosophical grounds.

Lewis: Yes—the exemption rate increased to 3 percent nationwide in 2022, and in 10 states it was over 5 percent.

Nuzzo: And just to be clear, I mean, the surveys show that still the vast majority of Americans support school based vaccine mandates. So there still is broad public support for vaccine mandates. That said, we are seeing a rise in exemptions. And we need to understand why that is.

Lewis: Surveys suggest that Americans’ trust in science declined during the pandemic. The news isn’t all bad, though: a recent Pew study found that most Americans still have positive views of childhood vaccines overall. But about half of parents of children four and younger say they worry that not all childhood vaccines are necessary.

Fischman: I’ve heard parents talk about this. In some ways, vaccines are a victim of their own success. We don’t see a lot of childhood diseases that vaccines prevent, so people have stopped worrying about getting them.

Lewis: Right. Plus, during the pandemic, COVID vaccines became politicized, and that spilled over to other vaccines as well. But Nuzzo, a parent herself, points out that health care providers haven’t done a great job addressing parents’ genuine concerns.

Nuzzo: You know, I think that there have been a lot of questions that we’ve not appropriately or sufficiently answered, that have left lingering doubts in parents minds, or have contributed to growing doubts in parents minds. And this is really something that I think we have to get ahead of, because if just left to its own can continue to grow and grow.

Lewis: Basically, Nuzzo says this is a wake-up call that we should be paying attention to parents’ concerns about vaccines, and addressing them before an outbreak happens.

Nuzzo: We need to take this as an important signal and start building the infrastructure and the trust that is necessary to bring people back to the side where they’re incredibly grateful for the advantages that vaccines offer.

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Fischman: Your Health, Quickly is produced by Tulika Bose, Jeff DelViscio, Kelso Harper, Carin Leong, and by us. It’s edited by Elah Feder and Alexa Lim. Our music is composed by Dominic Smith.

Lewis: Our show is a part of Scientific American’s podcast, Science, Quickly. Subscribe wherever you get your podcasts. If you like the show, give us a rating or review!

And if you have a topic you want us to cover, you can email us at Yourhealthquickly@sciam.com. That’s your health quickly at S-C-I-A-M dot com.

For Your Health Quickly, I’m Tanya Lewis.

Fischman:  And I’m Josh Fischman.

Lewis: See you next time.