Transcript: Racial Bias and Pulse Oximeters Part 2—What Went Wrong? | Johns Hopkins

The following is a transcript of Public Health On Call’s Special Series: Racial Bias and Pulse Oximeters Part 2—What Went Wrong?

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[Show Intro, Joshua Sharfstein: Welcome to Public Health On Call, a podcast from the Johns Hopkins Bloomberg School of Public Health, where we bring evidence, experience, and perspective to make sense of today’s leading health challenges. If you have questions or ideas for us, please send an email to PublicHealthQuestion@jhu.edu. That’s PublicHealthQuestion@jhu.edu for future podcast episodes.]

Lindsay Smith Rogers: Hi, I’m Lindsay Smith Rogers, and welcome back to our special series exploring racial bias in pulse oximetry.

In the first episode of this series, we looked into the history of the pulse oximeter as we know it today—a device that has been shown for decades to misread oxygen levels in patients with darker skin tones.

We do recommend that you listen to the first episode—linked in the show notes—before this one. But just to recap: Pulse oximeters are tiny sensors usually taped or clipped to a finger or earlobe that read a patient’s oxygen levels. These devices, which play an essential role in patient monitoring, rely on the passage of light to determine oxygen saturation. Because the design of these instruments make them susceptible to differences in skin tone, pulse oximeters perform differently in people from different racial and ethnic groups, depending on their skin tone. Specifically, for people with darker skin, the results are much more likely to be erroneous, potentially falsely reassuring clinicians that a patient is getting enough oxygen when, in fact, they are not.

And a note on language: These inaccurate readings are rooted in skin tone, not race. So a light-skinned Black person may get a significantly more reliable reading than someone with more melanated skin. But because of this issue’s disproportionate impact on Black people, in this series we often refer to the problem as racial bias or racial inequity.

COVID-19 brought the issue of racial bias in these devices into the headlines in 2020 and sparked fresh calls for change. Yet, still very little has changed as of 2024, and there isn’t a clear-cut solution. Why?

In this second episode of the series, Annalies Winny and Nicole Jurmo explore some of the many systemic factors that led to where we are today, including manufacturers, regulators and market forces, and systemic racism in medicine that goes well beyond this one piece of equipment. Let’s listen.

Nicole Jurmo: This is Nicole Jurmo. Remember the Hewlett Packard oximeter we learned about in the last episode? In many ways, it was what today’s pulse oximeters could have been: designed for everyone, regardless of skin tone. But instead, devices designed without consideration of skin tone differences captured the attention of investors, device manufacturers, and hospital purchasers, and became the norm.

It took a pandemic and a racial reckoning to really draw attention to the fact that these ubiquitous little devices—considered a lifesaving piece of clinical care—haven’t been doing their job well. Without knowing this, it’s easy to see what we saw during the pandemic—Black patients being sent home to die because their oxygen was supposedly within a “safe range”—as just a fluke, a tragedy that we just had to live through to learn from.

And yet, decades of evidence had already revealed serious flaws in those devices. Here’s a quick rundown:

In 1987, Meir Kryger, now a Professor Emeritus of Medicine at the Yale School of Medicine, published a study in his sleep lab comparing Hewlett Packard’s now-defunct ear-clip oximeter—which was designed to work in people with different skin tones—with Nellcor’s N-100 finger clip pulse oximeter, which wasn’t designed to account for racial bias.

Now, Kryger’s study wasn’t specifically looking for racial bias, but he found that the Nellcor’s pulse oximeter—which was described as selling, quote, like hotcakes—wasn’t as accurate or responsive as the HP design. But the broader medical community didn’t take any notice of the results.

Meir Kryger: The response from outside of the sleep monitoring community was zero. It's like they never got published.

Nicole Jurmo: It’s a trend that would continue.

In 1990 came one of the first studies to describe differences in pulse oximeter accuracy based on race. It found that pulse oximeters overestimated oxygen saturation to a greater degree in Black patients than in white patients. Then in 2005 and again in 2007, more research emerged finding the same thing: that pulse oximeters overestimated arterial oxygen levels in individuals with darker skin tones.

Fast forward to 2020.

[Archive clip, Newscaster: Dr. John, that was a very disturbing and upsetting report. African Americans are being hit disproportionately hard.]

[Archive clip, Woman: She flatlined in my arms…]

[Archive clip, Newscaster: African Americans being hit disproportionately hard by the virus…]

[Archive clip, Newscaster: In this chart, we can see African Americans represent 41% of COVID-19 deaths.]

Nicole Jurmo: University of Michigan researchers documented—this time on hospital COVID patients—that pulse oximeters were three times more likely to overestimate oxygen saturation in Black patients, than in white patients. Finally the issue was making headlines, making it hard to ignore, but studies had first revealed the problem decades ago. Why hadn’t more been done to address racial bias in pulse oximetry? Well, as they say, knowing is only half the battle.

In researching this series, we’ve come to learn that the racial inequities in pulse ox readings are a deeply embedded problem, and that several systemic factors have gotten in the way of change, including how they are regulated, and how clinicians and the public understand and use them.

Today we’ll look into three of those factors: the companies that make pulse oximeters, the regulators in charge of ensuring they are effective and safe, and the culture of medicine, research, and training that blinded generations of clinicians to the issue.

Let’s start with the device manufacturers. At any point over the last 4 decades—when research began to reveal these biases—manufacturers could have changed the technology to fix it. After all, manufacturers are tweaking and putting out new devices and bug fixes all the time. But when it comes to accounting for skin tone, by and large, pulse oximeters haven’t changed much since that Nellcor design from the 1980s, that was designed and calibrated for lighter skin tones.

It’s fairly well known that all sorts of light-sensing technologies can be problematic for darker skin tones. That’s a reality for various medical devices and processes, like detecting jaundice in babies, but also everyday devices like facial recognition technology, motion-sensor faucets, thermometers and photography, even hand soap dispensers: all originally designed to work best with light skin.

[Archive clip, Newscaster: A researcher at MIT found that the technology works best for white men. Users with darker complexions saw more instances of being misidentified.]

[Archive clip, Newscaster: Many facial recognition systems use the same data sets. If those sets contain mostly white faces, all the products that use that data can inherit those same biases.]

Nicole Jurmo: Just like the pulse oximeter.

So why didn’t manufacturers act sooner? We spoke to Mike Lipnick, an investigator in the University of San Francisco’s Hypoxia Lab and co-Director of the UCSF Center for Health Equity in Surgery and Anesthesia, where he runs a lab that independently tests pulse oximeters and advocates for transparency in pulse oximetry data.

Mike Lipnick: If you talk to most of the major manufacturers, they will tell you that they have devices that don't have this problem.

Nicole Jurmo: When we spoke to them, that’s pretty much what we heard. Individual manufacturers question whether their devices are really to blame, claiming that research outlining racial bias in pulse oximetry is flawed and fails to account for all the factors that could contribute to less accurate pulse ox readings.

In response to the headline-making 2020 University of Michigan research letter that found pulse oximeter readings for Black patients were less accurate than for lighter-skinned patients, the CEO of Masimo, one of the top manufacturers of FDA-approved pulse oximeters, wrote an op-ed titled “Pulse oximeters are not racist.” In it, he maintains that studies that use real-world clinical data—like the University of Michigan study—cannot statistically correct for all potentially important confounding factors that can impact a pulse ox reading. He also questioned whether certain health conditions like sickle cell disease or tissue damage, or the timing of measurements could be contributing to inaccuracies.

It’s true that skin pigmentation isn’t the only issue with pulse ox readings; there are multiple factors that could affect performance, such as poor circulation, skin thickness or temperature, tobacco use, and fingernail polish. But Jack Iwashyna, a Johns Hopkins ICU physician, and one of Tom Valley’s co-authors on that 2020 research letter, says these critiques don’t get to the heart of the issue.

Jack Iwashyna: Bringing up all these nuances about things clinicians can adjust for—finger positioning, fingernail polish—has the effect, intended or not, of distracting from the fact that we cannot adjust for patients’ race. None of these issues that are raised can explain the racial bias. It's a distraction.

Nicole Jurmo: He says that if the testing that uncovered racial bias in pulse ox readings is imperfect, those imperfections should result in inaccuracies for all patients, not just Black patients.

Jack Iwashyna: Over and over again, we find that there’s racial bias.

Nicole Jurmo: So, manufacturers haven’t made moves to address the technology because many still deny that there’s a problem in the first place, at least not with their own devices. And the data they use to back this up—their own data that they collect—has long been used by regulators to assess the performance of pulse oximeters.

Mike Lipnick is not convinced that their proprietary data is without bias.

Mike Lipnick: Every device ships with a little, like, booklet with, like, 20 pages printed onto one page. And it's, like, super fine print. And you can see in there some of the performance data. But almost all that performance data comes from the company. The companies either have their own labs, or they use for-profit labs that do the testing for them.

Nicole Jurmo: Plus, that data is collected in a controlled environment on healthy subjects. Daniel Cantillon, a physician and Masimo’s chief medical officer, says that this method allows them to control for more factors that might impact readings, and that the studies showing poor performance in darker-skinned patients—including research on Masimo products done by Lipnick’s lab—may be based on out-of-date devices…

Daniel Cantillon: When a lot of those studies are published, they're looking at older generation technologies. It really is about taking our latest technology and putting it in the hands of trusted partners that have the opportunity to prospectively gather that data in the most scientifically appropriate way, and then ultimately publish those results, which obviously takes time.

Nicole Jurmo: Masimo also stands behind their devices’ reading when it comes to skin tone. In 2022, after the University of Michigan paper came out, Masimo published their own analysis—using data from 2015 through 2021 from healthy volunteers, not patients—asserting that their devices work just as well on dark-skinned volunteers and light-skinned volunteers.

A big question here is why the data from manufacturers doesn’t mirror what’s seen in independent labs—that is, why some analyses show bias and others don’t. Some have theorized that that’s because manufacturers only looked at healthy volunteers who have good perfusion—that’s a healthy level of circulation of blood through the body—while sick patients may have more of a range.

But in an independent study that looked at 146 healthy patients of different skin tones, there were disparate readings. That study did find that the degree to which blood oxygen levels might be low could contribute to some bias—as in, the lower the levels, the less accurate the reading—and there was also evident racial bias. Jack Iwashnya says that he can’t prove why these differences show up in independent labs but not in industry-sponsored studies. This remains a big unknown, and a problematic one.

Another explanation that manufacturers have supplied for why they haven’t seen a need to change the technology is that they question whether the devices are being used properly and as designed. We spoke with Sam Ajizian, a physician and Chief Medical Officer at Medtronic, another top pulse oximeter manufacturer, about their devices and data. While acknowledging that technology matters and there’s room for improvement, he expects that provider and patient, quote, “education,” in how to best use the devices is key to the solution.

Sam Ajizian: We've got an opportunity here to really, really improve education around these devices, as well as reminding folks of how to use them, how to get them on correctly, how to position yourself as a provider, to make sure that device is giving you the best possible performance it can, and then amplifying in the community, what inaccuracies can occur, and to what degree, with different types of patient conditions.

Nicole Jurmo: According to Iwashyna, this strategy of denial and redirection follows a familiar playbook.

Jack Iwashyna: I'm certainly worried that manufacturers are deliberately sowing doubt about the findings that question their products. We know that big tobacco and the fossil fuel industry have intentionally sowed doubt. And I worry that that's what's going on here with pulse oximeters.

Nicole Jurmo: The bottom line is that top manufacturers stand by the performance of their devices, and only recently have come under pressure to consider what technological changes would improve pulse oximeters for all skin tones.

And a big reason why is that nobody, namely the U.S. Food and Drug Administration, told them they had to. The FDA's mission is to promote and protect public health.

Part of that mandate means monitoring safety and approving the release of products we use every day: foods, tobacco, drugs, therapeutics, cosmetics, and medical devices like the pulse oximeter.

When it comes to bringing clinical devices to market and rolled out in hospitals, the FDA’s stamp of approval is crucial. But until very recently, the agency’s standards for pulse oximeters have essentially ignored how skin tone can affect a pulse ox reading.

In November 2022, an FDA panel agreed that the available clinical evidence from real-world studies showed that pulse oximeters didn’t work as well in people with darker skin pigmentation.

[Archive clip, several FDA panel members: Yes I agree that there is a problem. It has clinical implications. / Yeah, I agree with everything that you said. / Yeah, just to strongly agree. / I agree, there's definitely a single signal there.]

Nicole Jurmo: Even more recently, in February of this year, FDA advisers from the Anesthesiology and Respiratory Therapy Devices Panel of the Medical Devices Advisory Committee proposed new recommendations for pulse ox clinical testing.

They recommended increasing the number of patients included in studies from at least ten to 24. And significantly, the recommendation includes having subjects across three cohorts of light, medium, and dark skin tone, as defined by the Monk skin tone scale, a measure of skin color developed with Google.

Unlike the previous scale, which originally only included white skin tones, and later added two darker skin tones, the Monk scale spans ten, and was designed right from the beginning to be inclusive of the entire range of skin pigmentation in the U.S.

But these recommendations aren’t yet official. So, what’s the latest? We got this update from Malvina Eydelman, the FDA’s Director for the Office of Health Technology, about the timeline for rolling out these recommendations. Her office oversees regulations throughout the life cycle of a range of medical devices, including pulse oximeters.

Malvina Eydelman: So this upcoming guidance is a priority to our center, and therefore we are actively working on this. The revised draft guidance on pulse oximeters is on our A list, which is a list of prioritized device guidance documents that we intend to publish during this fiscal year, FY 2024.

Nicole Jurmo: So why has the FDA waited so long to take action? Until recently, the FDA hadn’t agreed on a clear, universal way to even articulate the issue of skin tone measurement. That’s the reason why the recommendation of the Monk skin tone scale is a step forward.

Malvina Eydelman: And though scientific evidence suggests that there are some accuracy differences in pulse oximeter performance between lightly and darkly pigmented participants, there was no consensus on how or where to assess skin pigmentations.

Nicole Jurmo: That is, where on the body is the most reliable place to assess a person’s skin tone. Eydelman says that they’ve focused more on addressing these problems.

Malvina Eydelman: Since 2020, when it became apparent that the issue was indeed a significant public health concern.

Nicole Jurmo: So despite decades of evidence, the pandemic, and the research it inspired and questions it raised, really was a turning point for the FDA, like so many of us.

But what was going on up until that point? Let’s look at how medical devices like pulse oximeters are regulated by the FDA.

Today, pulse oximeters are cleared under what’s called the 510(k) review process. It’s a pathway that requires that manufacturers prove that their device is “substantially similar to another marketed device" cleared under similar rules. This pathway has many advantages for bringing devices quickly to market. That is exactly its goal. But there's a weakness, too. If the initial device is flawed, then other devices can be brought to market with the same flaws.

And it’s also important to note that the FDA’s regulation of medical devices was in its infancy when the first pulse oximeters—like the 1980s Nellcor model that formed the foundation of the models used today—hit the market and became widely used. According to the 510(k) database, there are now hundreds of pulse oximeter clearances based on old designs that were greenlit decades ago, when there was little regard for health equity or racial bias.

For pulse oximeters and other medical devices, the FDA also sets testing standards: the agency recommended that manufacturers include at least two, quote, “darkly pigmented subjects—or 15% of the study participants, whichever is larger—in their premarket studies. But this recommendation is not a requirement. And, as we’ve learned, skin pigmentation classification has historically been exclusively subjective, and often inaccurate. This is the standard still in use today.

Even with changes on the horizon, there are still potential blind spots in proposed regulatory updates to pulse ox standards, and some researchers wonder if the FDA’s changes go far enough. John Jackson is an associate professor in epidemiology at the Johns Hopkins Bloomberg School of Public Health.

He’s part of a team working to ensure racial equity is at the core of any new regulations adopted by the FDA for the medical device market, with a special focus on pulse oximeters.

John Jackson: It's those blind spots that I worry about, right? So it's the blind spots around the statistical modeling. But we want to make sure that the standards will be able to detect a meaningful degree of bias that would have clinical impacts, right? So whatever thresholds for bias that are set, that number one, that they'll be meaningful in a clinical sense, and not just be tied to the existing performance rates of these devices, and also, we want to be sure that there's clear guidance about how the evidence is produced so that we can be sure that we can compare across studies that nothing's being understated.

Nicole Jurmo: And to clarify, the proposed regulatory updates would affect hospital-grade pulse oximeters and over-the-counter devices that are used for, quote, “medical purposes.” It’s also unclear whether new standards will affect already-approved devices and whether the focus of testing will still be on healthy patients.

John Jackson: And I think this adds another layer to the equity lens, that it's not just skin tone, but we know that the devices performed differently for across levels of obesity, across levels of common comorbid conditions that have implications for vascular flow and vascular function.

And many of these conditions are over represented across among racial and ethnic minorities. So if we're thinking about the potential for bias, a large part of it could be driven by skin tone, but you could also see some of that bias play out because of the excess burden of comorbidities as well. So I think that's why the assessment across the skin tone is great, but we also want to see assessments across people with different comorbidities and also ultimately across racial and ethnic groups, to see what's the real world population-level impact.

Nicole Jurmo: The FDA also told us that it is working with UCSF and Stanford on two real-world studies assessing racial bias in pulse oximeters currently on the market. They now say they expect to release that data this summer. We asked the agency whether new data and changes to pulse ox standards would result in a recall of the devices already out there. They declined to comment on that until the final guidance is released.

But consumer advocates are already concerned that regulators’ relationship with manufacturers will play an outsize role in that calculation. Michael Abrams, a senior health researcher at the consumer advocacy group Public Citizen, described the FDA as a:

Michael Abrams: It’s a slow-turning ship. They're afraid to upset care providers who rely on these devices, and hospitals, and they're afraid to upset the big device makers as well.

Nicole Jurmo: So all this thorny debate about who’s got good data and who’s responsible for fixing pulse oximeters, gets even stickier because device manufacturers have a close relationship with regulators and organizations that create international standards for the devices. Some say too close.

For example, a Masimo representative sits on the FDA’s Anesthesiology and Respiratory Therapy Devices panel. That means he is an adviser to the agency about the safety and effectiveness of pulse oximeters. And Masimo, along with other top pulse ox manufacturers Medtronic and Philips Life Sciences, all have representation on a global standard-setting body called the International Organization for Standardization. It’s in charge of outlining common standards for anything from freight containers to workplace safety to medical devices like ventilators, thermometers, and pulse oximeters, with the aim of ensuring quality. And the FDA incorporates ISO’s pulse ox standards as minimum standards into their guidance.

Sam Ajizian from Medtronic says manufacturers deserve to be part of conversations around standards.

Sam Ajizian: If the FDA is not listening to their manufacturing partners to bring devices to market, they may have a significant blind spot. So I think the listener has to understand, it's important for us to be at the table, they need to trust the FDA to not enter into any sort of conflict of interest type of relationship, and our compliance system, as well, prohibits us from doing anything like that.

Nicole Jurmo: Meir Kryger, who we met earlier, doesn't have that level of trust.

Meir Kryger: There's an obvious conflict of interest. On the other hand, the FDA may not have the in-house expertise to develop comprehensive standards. So that's where the dilemma lies, and maybe they need to have a change in how they develop standards.

Nicole Jurmo: As the FDA wrestles with how to proceed today, let's turn to the third piece of the puzzle: the broader medical community. Why wasn't there outrage at the failure of pulse oximeters and a demand for change?

As with most of what we’ve found with this issue, what’s past is prologue. In other words, as much as medicine has advanced, where we are with the pulse ox is a direct result of a system that was never designed for non-white people.

Take medical research. In 2021, Francis Collins, then-head of the National Institutes of Health, the largest single public funder of biomedical and behavioral research in the world, apologized for racism in research funding.

[Archive clip, Francis Collins: I would like to take this moment also to those individuals in the biomedical research enterprise who endured disadvantages due to structural racism, I am truly sorry. And NIH is committed to instituting new ways to support diversity, equity, and inclusion, and identifying and dismantling any policies and practices that may harm our workforce and science.]

Nicole Jurmo: This structural racism has had a lasting legacy not just on which researchers were funded—in 2020, for example, less than 3% of NIH’s principal investigators were Black—but on what topics were considered relevant and useful.

Andrea Deyrup: A lot of it has to do with, you know, what we might call the “Old Boys network.” I mean, there’s a reason there's this legacy of entitlement, of power, of resources, of connections.

Nicole Jurmo: That’s Andrea Deyrup. She’s a professor of pathology at Duke University School of Medicine who writes medical textbooks, and advocates for problematic assumptions about race to be removed from them.

Andrea Deyrup: When we talk about systemic racism, the point is that it's systemic. We don't see it, and it's the water we swim in. The voices of the people who aren't in that positionality are drowned out or muffled, aren't listened to, or there aren't enough.

Nicole Jurmo: Assumptions are made that inadvertently deprioritize and oversimplify what it means to live in a body that is not white. In the case of pulse oximeters, despite early studies documenting racial bias, medical schools weren’t teaching it because there was an assumption that it wasn’t clinically significant.

But Deyrup did her residency on the south side of Chicago, which serves a large African American population, and never learned about racial bias in pulse oximetry, even though it would certainly have been clinically significant there. And Noha Aboelata, a family physician who trained at a historically Black college, and is currently the CEO of Roots Community Health Center in Oakland, California, works in a community where it also would be clinically significant.

Noha Aboelata: I've been serving communities of color my entire career. I've used that device like a thermometer or blood pressure cuff; it's a vital sign. And the fact that, you know, we didn't know it, we weren't trained on it in school, or, you know, or anywhere. I started calling all my colleagues. And I was calling ED physicians, pulmonary critical care, everyone. Nobody knew about it. But this is a perfect example, a contemporary example of how systemic racism in health care works and how we overlook things.

Nicole Jurmo: Tom Valley and his colleagues had a similar experience, never being taught about the problem with pulse oximeters. Once learning about previous research that mirrored his own, Valley questioned why this piece of information that could have saved lives wasn’t more widely known.

Tom Valley: And so clearly, there was a problem in terms of what types of research we prioritize, what types of research we disseminated. And so I think there is an opportunity here for us to evaluate what we're teaching in medical schools, what we deem is important. Not just medical schools, nursing schools, any really school that trains a health care clinician, to make sure that folks know about these potential problems with technology.

Nicole Jurmo: Amy Moran-Thomas—the MIT professor who wrote that influential Boston Review article about the history of racial bias in pulse oximetry that helped inspire the latest studies—she told us that this information actually was in at least one critical care medical textbook she found.

Amy Moran-Thomas: They told me, “we never teach that part of the textbook.”

Nicole Jurmo: But fundamentally, perhaps the issue was deprioritized because of who was most affected: darker-skinned patients. Jack Iwashyna again:

Jack Iwashyna: The reality is function in white patients was considered the norm, and function in Black patients was considered a clinical nuance that certain experts were supposed to know about. That’s a perfect example of white supremacy, right, assuming that something has to work for white folk, and that white folk are the norms, but if it works in other populations, that's a nice-to-have, not a must-have. And it's a perfect example of whether or not you really think Black lives matter.

Nicole Jurmo: And as Moran-Thomas pointed out, those decisions about what to teach, they’re a reflection of values that influence every generation of medical practitioners, and ultimately, the patients that those practitioners are supposed to serve.

Amy Moran-Thomas: That space between what is known on paper and what is actually taught in medical school, that’s culture.

Nicole Jurmo: And beyond medical schools, culture—made up of powerful invisible forces that shape belief systems and values, and what gets attention—will be the driving force of change in pulse oximetry. It’s already behind the limited changes that are happening now. And while it’s slow-going, the needle is moving.

As Simar Bajaj, the science historian and cardiothoracic surgery research fellow who we met in the last episode, put it:

Simar Bajaj: There's plenty of examples of devices, medicines, algorithms, that, out of convenience or simply this neglect, bias was allowed to stay in. What is exceptional about the pulse oximeter is that people suddenly care about it.

Nicole Jurmo: And those people aren't just regulators, manufacturers, or members of the medical establishment.

What other forces are at play to turn this fresh wave of concern about pulse oximeters into more equitable, better-understood, and more trusted devices? And who is leading those efforts? That’s what we’ll tackle in episode 3.

Lindsay Smith Rogers: Thanks for listening to episode two of our three-part series. Episodes one and three are linked in the show notes. Special thanks to Annalies Winny and Nicole Jurmo for co-producing this series.

[Podcast Credits, Joshua Sharfstein: Public Health On Call is a podcast from the Johns Hopkins Bloomberg School of Public Health, produced by Joshua Sharfstein, Lindsay Smith Rogers, Stephanie Desmon, and Grace Fernandez Cecere. Audio production by JB Arbogast, Holly Cardinell, Spencer Greer, Matthew Martin, and Phillip Porter, with support from Chip Hickey. Distribution by Nick Moran. Production management by Catherine Ricardo. Social media is run by Grace Fernandez Cecere. Analytics by Aliza Rosen. If you have questions or ideas for us, please send us an email to PublicHealthQuestion@jhu.edu. That's PublicHealthQuestion@jhu.edu for future podcast episodes. Thank you for listening.]