Measles and public health: Risks, prevention, and response to current outbreaks

[00:00:25]

ELENA RENKEN: Hello, everyone, and welcome to SciLine’s media briefing on measles. With over 300 cases reported in 2025, we’ll cover who measles affects most, how the disease is spread and tracked, and details about the vaccine against measles. I’m Elena Renken, SciLine’s manager of journalism projects and multimedia.

A little context about what we do at SciLine. We make it as simple as possible for reporters to get scientific evidence and expertise into their stories. Whether that’s on a topic like measles or in a story where the science angle is less obvious, such as in coverage of immigration or education. SciLine is a philanthropically funded, editorially independent nonprofit based at the American Association for the Advancement of Science, and everything we do is free. We have a range of resources available on sciline.org, including interview opportunities and a toolkit to help with reporting on the key issues of 2025. And if you’re working on a story that could use some context from an expert, you can click the blue I Need an Expert button on our website, and we’ll look for a scientific source for you with the right research background who’s available to speak before your deadline.

Now, before we start, I want to give our three panelists a chance to introduce themselves and their areas of research. Dr. Tan, would you go first?

[00:01:48]

TINA TAN: Absolutely. Hello, everyone. I’m Dr. Tina Tan. I’m a professor of pediatrics at the Feinberg School of Medicine of Northwestern University. I’m a pediatric infectious diseases physician at Lurie Children’s Hospital of Chicago, and I’m president of the Infectious Diseases Society of America. And my area of research actually has to do with vaccine-preventable diseases and vaccines, especially with regards to education of patients and healthcare providers. I also have a lot of research that I’ve done in pneumococcal epidemiology and impact of the vaccine on that, as well as pertussis.

[00:02:35]

ELENA RENKEN: Thank you. And Dr. Winter, would you introduce yourself next?

[00:02:39]

AMY WINTER: Absolutely. Good afternoon, everyone. My name is Amy Winter. I’m an assistant professor at the University of Georgia and the Department of Epidemiology and Biostatistics. I’m an infectious disease modeler, and my research takes a policy relevant approach to answering questions on transmission and control of infectious diseases, particularly measles and rubella.

[00:03:03]

ELENA RENKEN: Thank you. And Dr. Higgins, would you go ahead?

[00:03:06]

DAVID HIGGINS: Yeah. Hi, everyone. My name is Dr. David Higgins, and I’m a practicing pediatrician and a health services researcher at the University of Colorado Anschutz Medical Campus. My area of research is on vaccine hesitancy, confidence, and uptake, and ways to improve that. I also volunteer my time with Immunize Colorado, which is a nonprofit looking to improve vaccination rates in Colorado, as well as the American Academy of Pediatrics.

[00:03:40]

ELENA RENKEN: Thank you all. Now I’ll have a brief conversation with each of our panelists before we take questions from the audience. We’ll be collecting those questions throughout the briefing, so journalists, please submit them at any time by clicking the Q&A icon at the bottom of your Zoom screen. And please note if you’d like your question directed to any specific speaker.

[00:03:59]

ELENA RENKEN: We will be posting a recording of this briefing on our website later today, and a transcript will be added in the next few days. Now we’ll begin with you, Tina. First off, what causes measles, and who does this disease primarily infect?

[00:04:15]

TINA TAN: So measles is an acute viral infection that is caused by the measles virus. And humans are the only natural host of the measles virus, and persons of all ages can be infected, with the persons at the highest risk for developing severe disease being those that are too young to be vaccinated and those that are unvaccinated. And this includes children under five years of age, especially those under one year of age, pregnant people, unvaccinated adults over 20 years of age, persons with underlying immunocompromising conditions, and persons that are severely malnourished. So these are all the people that are at the highest risk for developing severe disease.

[00:05:05]

ELENA RENKEN: And what are the symptoms and long-term effects of measles? And are they especially harmful for certain groups?

[00:05:11]

TINA TAN: So a measles infection starts with symptoms of fever, cough, runny nose, and redness of the whites of the eyes, known as conjunctivitis, that is followed three to five days later by the development of a red blotchy rash that begins on the face, usually around the hairline, and then spreads down the body and out toward the arms and legs. And prior to the development of the rash, patients can also develop whitish lesions on their oral mucous membranes across from their molars, which are called kolpik spots. Persons are contagious from four days prior to the appearance of the rash through four days after the appearance of the rash, with immunocompromised patients staying contagious for a longer period of time.

And the complications of measles include ear infections, pneumonia, a whooping cough, profuse diarrhea. You can also get deafness, you can get blindness, you can get inflammation of the brain, known as acute encephalitis, and then unfortunately people can also die. And the long-term complications are really permanent hearing loss, blindness, permanent neurologic deficits, and developmental abnormalities in patients that do develop the encephalitis. Now there is a type of encephalitis that’s known as measles inclusion body encephalitis that occurs in immunocompromised patients, and this encephalitis may develop within a year of a person having a measles infection, and this can lead to permanent and progressive neurologic dysfunction.

There also is a rare degenerative complication of measles that’s known as subacute sclerosing panencephalitis, which is a degenerative central nervous system issue that is characterized by behavioral and intellectual deterioration and seizures. And this can develop seven to 11 years after a person has had a measles infection, and the highest rates of this rare complication are seen in children that have had the measles infection prior to the age of two years.

[00:07:46]

ELENA RENKEN: Very good to know, thank you. And what should someone do if they think they have been exposed to someone with measles?

[00:07:53]

TINA TAN: So if a person thinks that they’ve been exposed to measles, they need to immediately contact their healthcare provider to determine several things, to determine if they need further evaluation, to basically discuss if they’re up to date on their vaccines or if there are other preventative measures that need to be taken. Because persons that are not vaccinated and are exposed to measles can receive a dose of the MMR vaccine within 72 hours of exposure, and this will provide them with protection and decrease their risk of actually developing measles.

And then infants between six and 11 months of age can also receive a dose of MMR vaccine, but that doesn’t count toward the two recommended doses that they need to receive. And for infants under six months of age, for pregnant women, or for persons with immunocompromising conditions who cannot get the measles vaccine, they can receive either a dose of an intramuscular immunoglobulin or intravenous immunoglobulin if it’s within six days of their exposure to measles. And this will provide them with protection and decrease their risk for developing measles infection.

[00:09:19]

ELENA RENKEN: And what is it that makes measles infection so serious?

[00:09:23]

TINA TAN: Well, one thing about measles that makes it so serious is it is the most highly transmissible infection that a person can get. A person with measles can transmit the disease to as many as 18 other susceptible individuals with transmission in a household setting of 90% or higher. Infection also places a person at risk for severe complications like pneumonia, the encephalitis, which is the brain swelling, with neurologic deficits and seizures. You can get permanent deafness, you can get permanent blindness, and you can die from the disease. And we also know that the infection significantly weakens a person’s immune system, which places them at very high risk for other potentially serious infections.

[00:10:18]

ELENA RENKEN: Thank you, Tina. And now some questions for you, Amy. How does measles spread and how fast? And how does that compare to other infectious diseases like influenza, chickenpox, and COVID-19?

[00:10:33]

AMY WINTER: Yeah, thanks. So to add on to what Dr. Tan said, measles is one of the most highly contagious infectious diseases. It’s spread primarily through respiratory droplets and airborne transmission, meaning when we cough or sneeze, we expel droplets that land on surfaces that others may touch and then eat with those hands or touch their eyes and via aerosolized particles. In fact, the measles virus particles can remain airborne for up to two hours after an infected person leaves the area, which makes transmission highly efficient in crowded settings. And also, as Dr. Tan mentioned, measles can spread before symptoms. In fact, people can be infectious up to four days before they show symptoms, also increasing the likelihood of transmission.

So, how does this compare to other infectious diseases? A key measure we think about a lot as epidemiologists in terms of how infectious diseases spread is the basic reproduction number, which represents the average number of people one infected individual is expected to transmit the disease to in a fully susceptible population. One single measles case is thought to cause on average 12 to 18 secondary cases in a completely susceptible population.

How this compares to other diseases such as seasonal influenza, which is R0 between 1.3 and 2; chickenpox, R0 between 7 and 10; and then COVID-19, there’s a decent amount of variability by the different variants, but somewhere between 2 and 10. So measles, as I said, is very, very highly contagious and spreads faster than other diseases.

[00:12:12]

ELENA RENKEN: Excellent, thank you, and that R0 is the reproduction number?

[00:12:15]

AMY WINTER: The basic reproduction number, that’s correct.

[00:12:18]

ELENA RENKEN: Thank you. What control measures have been keeping measles levels relatively low in recent decades?

[00:12:26]

AMY WINTER: Yeah, so measles has actually been declared eliminated in the U.S. as of 2000. And in order to keep that elimination status, it means that there needs to be no continuous transmission chain for 12 months or more, and a transmission chain is when you can link one infectious individual to the next. So, it’s really legitimately amazing and applaud worthy that we’ve been able to eliminate the disease and keep it eliminated in this country. And some of those key control measures that are contributing to this is, most importantly, the high vaccination coverage that we’ve historically seen in the United States. Measles vaccine is safe, it’s effective. With one dose, it’s just 93% effective, and with two doses, it’s 97% effective. In fact, it’s also believed to offer lifelong immunity from disease.

So, all 50 states do have these state laws that require children entering childcare or public schools to have certain vaccinations. And that’s one of the things that has kept measles vaccination high, particularly in children entering school. Measles vaccination coverage among U.S. kindergartners, according to the CDC in 2019 and 2020 was 95.2%. It has dropped since then, but in terms of what’s contributing to these control measures, certainly high vaccination coverage. This in coordination, high vaccination coverage allows indirect protection for susceptible individuals. And this is a concept us epidemiologists think of as herd immunity, which means that a high level of immunity in the population reduces the overall amount of measles virus available to infect those who are not immune. So basically, it allows indirect protection. So high vaccination coverage, indirect protection of susceptible individuals as a result of high vaccination coverage. And the third thing is that we have a very sensitive and effective surveillance system that’s able to identify, publicly communicate when they see cases, and then stop transmission chains by isolating the case or vaccinating individuals around them.

[00:14:35]

ELENA RENKEN: You mentioned that surveillance system. How do you surveil a population for measles? And how do researchers estimate the number of infections based on that data?

[00:14:45]

AMY WINTER: Right, so it depends on the country, but certainly here in the U.S., we have epidemiologic and laboratory-based surveillance systems where confirmed measles cases are reported to the CDC by state health departments through a system known as the National Notifiable Diseases Surveillance System. In the U.S., to my knowledge, there’s no additional estimation that takes place. The CDC assumes that we are capturing all cases. And this is for two good reasons.

One is measles is highly recognizable disease. And then the second is that our surveillance system here in the States, at least up through 2024, has been performing very, very well. It’s very sensitive. It hits this criteria in terms of tracking the surveillance indicators attached to the cases, and it’s able to capture transmission chains of multiple sizes.

[00:15:38]

ELENA RENKEN: Very good to know. Thank you. Let’s now turn to you, David. How does the measles vaccine work, and how effective is it over time?

[00:15:47]

DAVID HIGGINS: Yeah. So the measles vaccine works in a similar way to other vaccines. It stimulates the immune system to produce protective antibodies against the measles virus without actually causing illness. The MMR vaccine, which protects against measles in addition to mumps and rubella, is typically given in two doses. The first, as a pediatrician, I give to patients at 12 to 15 months old and the second around four to six years old. And as others have already said, after two doses, the vaccine is incredibly effective. It is estimated to be 97% effective at preventing measles, and it’s often said that this is effective for life. The immunity that a person receives from the measles vaccine is long lasting. We call it very durable. And booster doses are not routinely needed for those who receive the two-dose series when they’re children.

[00:16:46]

ELENA RENKEN: And what do data show about trends in vaccine uptake? And can you talk about herd immunity? Does that herd immunity for measles cover gaps in vaccine uptake?

[00:16:56]

DAVID HIGGINS: Yeah, great question. So first, trends in vaccine uptake, what we’ve seen in recent years is that measles vaccination rates, MMR vaccination here in the United States, has declined. Now, it’s declined in many parts of the world, and this is due to a variety of factors, including misinformation and vaccine hesitancy that often captures the headlines, but also disruptions to access and supply chains from the COVID-19 pandemic that occurred around the world and in the U.S.. And the MMR vaccine coverage, we say in public health that it needs to be at least 95% in the community to really maintain that community immunity.

Like Dr. Tan mentioned, there are patients who either cannot get the vaccine or for whom when they get the vaccine, it doesn’t give that protection that we hope it would. This includes people like infants, those with weakened immune systems, people who have cancer and are immune compromised. And so they are really relying on community immunity, on others in the community getting vaccinated to protect them. And we know, and this is why we’re here today, is that in some communities we have seen vaccination rates drop so low that we’re seeing a resurgence and spread of measles outbreaks. I like to say that when vaccination rates drop in a community, it is not a question of if, it’s a question of when measles is going to come because it is so incredibly contagious.

And my last point on this is that often you will look at national measles vaccination rates or state level rates. We know that these outbreaks happen in local communities. And so even if a state has a rate that is at the goal, that might not mean that a local community, that a local county is at that goal, and they are susceptible to having an outbreak.

[00:19:07]

ELENA RENKEN: Thank you. What is the role of vitamin A in treating measles?

[00:19:13]

DAVID HIGGINS: Yeah, so you’ve seen this in the news a lot lately. And prior to the past couple of months, you probably hadn’t even heard about vitamin A in treatment for measles. So I want to start by emphasizing vitamin A does not prevent measles and it is not a substitute for vaccination. I want to make that really clear. And I think it’s important to make that really clear in all of your media. It does play a role in reducing the severity of measles infections, especially in people who are deficient, OK? But consider it a supportive treatment.

When children or adults get infected with diseases such as measles, we do all sorts of things to support their body, to help them recover from the illness. And we know that if somebody is deficient in vitamin A or if measles causes a deficiency, that can lead to worse outcomes. And it’s for that reason that the World Health Organization, they recommend vitamin A supplementation for children with measles. And most experts here in the U.S. agree. However, the best way to prevent measles is vaccination. Vitamin A is not an alternative to vaccination.

[00:20:29]

ELENA RENKEN: Good to know. Thank you. And what does the evidence say about potential side effects of the measles vaccine? And how has misinformation impacted vaccine uptake?

[00:20:39]

DAVID HIGGINS: Yeah, the MMR vaccine is incredibly safe. Decades of research confirming that it is incredibly safe. Like all vaccines, it can cause mild temporary side effects. A low-grade fever, it can cause a rash, soreness at the injection site. And serious side effects are extremely rare. What you will see in the headlines and what we’re all hearing a lot about right now is the MMR autism myth. This gained mainstream attention in the late 1990s after a fraudulent study was published. And this has been thoroughly disproven by numerous, dozens of large-scale studies, including millions of children. There is no link between the MMR vaccine and autism or other long-term health issues. It is a very safe vaccine.

[00:21:37]

ELENA RENKEN: Thank you all so much for this information. And now I’ll go ahead and pose questions to our full panel here. I want to remind reporters in the room to submit questions using the Q&A box at the bottom of your Zoom screen. First off, in the recent news coverage of measles cases that you’ve seen, what advice do you have for reporters in their coverage?

[00:22:01]

TINA TAN: So I think it’s just really important that the proper information is reported and have people understand, as Dr. Higgins brought up, that the measles vaccine is the only way really to prevent and protect individuals against measles. And that measles is not a benign disease. There can be complications associated with it. But the vaccine is safe and effective and really can be used down to six months of age if need be.

[00:22:46]

DAVID HIGGINS: I would add to that, that, when possible, when you’re reporting on this, avoid repeating misinformation. And also try to avoid what we call false balance, right? This is when it’s presented in a way that decades of scientific evidence, tens of thousands of researchers and physicians and public health, have said this is safe and effective. And you present that side of it. And then the other side that might be built on a myth or a fringe ideology as being a 50-50 tossup on what this could be. And so how you present that does matter.

[00:23:30]

AMY WINTER: Maybe I’ll just add to that. In terms of the—there’s a global perspective here, right? So the states have been quite successful in reaching elimination and maintaining elimination. It speaks to our public health services, our surveillance systems. I work mostly in other countries where the big issue is access, right? So the idea that we’re struggling to make sure that we don’t spread misinformation so that individuals have what they need in order to vaccinate their children. I guess the last thing I might just add is that measles outbreaks can evolve rapidly as we know because they’re so transmissible. So just try to stay updated with information to provide the most current and accurate reporting.

[00:24:20]

DAVID HIGGINS: I would love to add to what Dr. Winter just said. I think this is great. We have been really successful in the United States because most parents vaccinate. Sometimes we miss that message. Most parents are vaccinating their children, overwhelming majority, over 90% are vaccinating their children against measles. And in this day and age, it’s hard to find over 90% of people agreeing on anything. And so sometimes we forget to talk about that when we’re appropriately highlighting the challenges.

[00:24:55]

ELENA RENKEN: Thank you. And our first question for you from The Arizona Republic, are all adults protected from measles if they were vaccinated as children? Are there any adults who should get a booster? And will a booster hurt an adult who isn’t certain about their MMR vaccine status?

[00:25:15]

TINA TAN: So basically, the vaccine that children got like in the 1960s is different from the vaccine that we use today. And most adults during that time period would only have gotten 1 dose of measles vaccine, given the fact that the second dose of measles vaccine was not added to the schedule until after there was a very large outbreak here in the United States in the late ’80s and early ’90s. So if there is an adult who’s going to be traveling internationally, or if they’re living in an area where there is a measles outbreak, there’s no harm in getting a booster dose or a second dose of vaccine to protect yourself.

[00:26:10]

ELENA RENKEN: Thank you. And next from Colorado Public Radio. Colorado has not yet had a measles case, but nearby states have. When it has its first case, which seems inevitable, what would the ideal state response look like?

[00:26:25]

DAVID HIGGINS: So I’ll take this question, being here in Colorado. This is what I’d love to see. So several things need to happen. First, the communication needs to be timely, rapid, but clear and community centered. And yes, from the top down, from the top health and government leaders, there needs to be clear communication. But also there need to be efforts within communities to use trusted messengers to quickly disseminate clear evidence-based communication. And often that –that is sometimes more challenging, and often that gets overlooked. These types of outbreaks frequently occur in communities, in small communities. And it’s important that we are quickly getting information to those communities from someone that they trust. And that might not always be the top health official or governmental official. So while the messaging needs to be consistent from the top to the bottom, we need to make sure that people that are on the ground in those communities are disseminating good quality information.

[00:27:47]

ELENA RENKEN: From the Ledger-Enquirer in Columbus, Georgia—with the recent cuts at the federal level, especially at the CDC, does the public have access to reliable and timely information, or where can people go for updated info?

[00:28:03]

AMY WINTER: So the CDC is updating their website, I think, weekly at this point. Just Google CDC measles, and there’s a link that specifically at the very top says cases were updated as of the specific date. So as of right now, there’s been 301 confirmed cases, one confirmed death, and then one suspected death that they’re looking into.

[00:28:29]

DAVID HIGGINS: I would add that a lot of us clinicians and anyone in health that’s looking for good resources, there are some other great organizations that have excellent resources. And I’ll list a couple of them off the top of my head, and Dr. Winter, Dr. Tan can add to those. But one that I’m involved with, the American Academy of Pediatrics, has some excellent resources. Immunize.org has some excellent, reliable information about things like vaccines. And then on the adult side, there are some other organizations as well. AAFP, the American Academy of Family Physicians, American College of Physicians has some information, and I’m probably missing a couple. But those are some of the resources that I say, okay, these are reliable, good resources that people can trust to give them information in this time.

[00:29:22]

TINA TAN: Yeah, other sites would be the Infectious Diseases Society of America, also the National Foundation for Infectious Diseases. They also have wonderful resources on their websites to really help individuals with information about these different diseases and the vaccines.

[00:29:49]

ELENA RENKEN: Thank you for those resources. Our next question here is from the Albuquerque Journal. What community strategies have proven effective in positive messaging about vaccines in areas where uptake is low?

[00:30:05]

DAVID HIGGINS: So I’ll start with saying that the evidence shows that a clear recommendation from a trusted messenger, and often that is pediatrician, a physician, or another healthcare professional that a family trusts, is still the most important thing for improving uptake as far as communication. And I can’t emphasize that enough, that trusted messengers in the community, who the message is coming from is really, really important. And so building the trust in the community, building the coalition and collaboration between, say, public health leaders that might not be actively in the community and the people who are on the ground in the community is really important.

[00:30:58]

TINA TAN: Yeah, I really, really like to emphasize what Dr. Higgins said, because we know that the most trusted messenger usually is the PCP, but there could be other messengers in the community that the individuals in that community really trust a lot. And to have them put out a message where there’s accurate information can really help people understand the need for why things are done the way they’re being done.

[00:31:44]

DAVID HIGGINS: And I’d like to add that I think it’s really important to recognize how we are communicating, not just what we’re communicating. So obviously the facts, the evidence matters. It’s really important that we get our evidence correct. But how we approach the public, when we approach the public as partners in trying to help them and their communities thrive, when we avoid being dismissive, when we avoid being confrontational, that is really important. We need to approach them as partners, that we are trying to work together to help their communities, to help their families and their children thrive.

[00:32:31]

ELENA RENKEN: A question here from Baptist News Global. What common arguments are anti-vaxxers making in response to the current measles outbreaks? And what does research tell us about those claims?

[00:32:44]

TINA TAN: So many of the people that are either very vaccine hesitant or anti-vaccine really have a lot of concerns about what Dr. Higgins brought up with regards to vaccines cause autism. There still is that major concern that people have. They also feel that they don’t want to introduce foreign materials into their child’s body and that a natural infection is going to help them more. And they are very, very concerned about other types of side effects and the fact that many of the anti-vaxxers are saying that vaccines are not effective.

[00:33:32]

DAVID HIGGINS: What I’ve also seen in addition to those really specific things like autism is sometimes it is just a general distrust of the medical institution and of medical recommendations. And in some of the interviews and things that I’ve seen in the current outbreak, that is some of the sense that I’ve gotten. And I experienced patients sometimes where that’s the case, where when I explore their concerns and questions, it might not be a specific thing. It might just be kind of a general distrust. We have also seen some talk about things like, well, contracting measles is actually better for you. And concerns like that are not actually new. We have heard these concerns for decades and worked hard and continue to work hard to try and clarify why they’re not true. Why vaccination is the most effective, arguably the only effective way to prevent measles, and it’s incredibly safe.

[00:34:42]

TINA TAN: Yeah, I mean, I think the other thing too is that a lot of people get a lot of their information from social media. And some of those things that are posted on social media are completely incorrect. But you really have to listen to the patient and to understand why they have concerns about getting the vaccine or why they don’t want to get the vaccine. And really try and empathetically speak with them to try to provide them with the correct facts and give them correct information and resources that they can look at so that they can understand why vaccines are safe and effective.

[00:35:31]

ELENA RENKEN: A related question from Texas Public Radio. How would you recommend responding to non-medical messages that vaccination is an infringement of personal liberty?

[00:35:46]

TINA TAN: So there are a lot of people that feel like, as Dr. Higgins brought up, they don’t trust the medical establishment. They don’t trust the government. They want to make all the decisions on their own. And basically, this is a decision for them. It’s not like in that particular situation you’ll go into the room and say you have to get this vaccine. But again, it really is discussing with them what their concerns are. And then basically trying to explain to them why this is the best thing for themselves and their families in terms of protecting and preventing them from getting a disease.

[00:36:33]

DAVID HIGGINS: Yeah, I speak to families every week that are concerned about vaccinating their child. And when I do, one of the really important components of effective communication is that I respect their autonomy. They do have a decision, and it’s ultimately their decision whether they vaccinate their child or not. I really respect that. And I emphasize that when I’m talking to them. At the same time, I have a responsibility as a physician, as their pediatrician, to recommend the measles vaccine. To recommend it because it is critical to helping prevent a life-threatening illness and help their children thrive. And in my opinion, I believe that we in the public health community and the nation’s health institutions also have a responsibility to share that same message. That doesn’t need to infringe on their autonomy to ultimately make the decision for what’s best for their child. But we have a responsibility to share the message of the overwhelming benefits of the measles vaccine with the public.

[00:37:45]

AMY WINTER: Maybe I’ll just add the population perspective as the epidemiologist in the group. And I don’t know how many this speaks to, but it’s a global—it’s a public good to get vaccinated, right, because of the individuals who can get vaccinated because they’re too young or they have immunocompromised types of diseases. By you getting vaccinated and your healthy child getting vaccinated, you’re indirectly protecting them. And that’s something I know in the States we think a lot autonomously, but it is a public good as well.

[00:38:18]

DAVID HIGGINS: Yeah, and you know what? I have families who that actually is one of the reasons, one of the many reasons they choose to vaccinate their children, right? Because they actually value their community and want to help protect their community.

[00:38:32]

TINA TAN: Right, they feel a moral responsibility.

[00:38:35]

DAVID HIGGINS: Yeah.

[00:38:39]

ELENA RENKEN: A question here from The Dallas Morning News. How long do measles outbreaks last and how large can an outbreak become? For the Texas, New Mexico current outbreak, do you have a sense of how much longer this will last?

[00:38:53]

AMY WINTER: That’s a great question. Measles outbreaks can be as large—imagine whatever sort of size of the susceptible population exists and in terms of how connected they are, it could be as large as infecting every single one of those or most of those individuals, up to 95% possibly. So it can be very, very large. In terms of how long it’s going to last, the hope is that it doesn’t last longer than 12 months because then we lose our elimination status. The last time we were closest to losing our elimination status was in 2019. It’s hard to remember pre-pandemic, but we had a lot of decent sized measles outbreaks all over the world, including in the States. It was in Disneyland. We may have forgotten since then. But in that instance in 2019, the longest lasting transmission chain was 63 days. So we had cases throughout the year. But in terms of what an outbreak the CDC describes as an outbreak, it’s transmission chains that are 3 or greater cases.

[00:39:54]

ELENA RENKEN: A question here from Georgia Public Broadcasting directed to Dr. Winter, if you’re able. How confident are you in the surveillance of measles at the state level after an initial case within the state? And are there any risks that if fewer kids get vaccinated, we’ll know less about how the disease is spreading? Or what are your concerns about the future of modeling if you see fewer people vaccinated?

[00:40:25]

AMY WINTER: My confidence in Georgia is the same as the rest of the states. I mean, measles confirmed cases are passed up to the state health department who then notifies the CDC through that surveillance system. I don’t think there’s any particular reason hopefully that Georgia is any different than the remaining states, hopefully. In terms of are there less kids who get vaccinated we’ll know less about how the disease is spreading, not to my knowledge. With less children being vaccinated, there is possibility that we have longer sort of transmission chains, that there’s more cases that we will see. But given how good quality our surveillance system is, I still suspect that we’ll be able to pick up those cases. In terms of what are my concerns about the future of modeling these diseases, yeah, I’m not any more concerned today as I was last year.

[00:41:27]

ELENA RENKEN: Thank you. And a question here from the Montana Free Press. Montana does not collect immunization data from schools. How does a lack of data at the local level impact disease outbreak preparedness?

[00:41:41]

DAVID HIGGINS: Well, I will tackle this one, having previously been a pediatrician in Montana. I worked in Montana for several years, and at that time, this data was reported. And I’m disappointed to see that it’s not because it absolutely affects the ability at the community level, at the local level, to effectively prevent and respond to measles outbreaks. Like I said, right at the very beginning, we talk about sometimes vaccination coverage at a state level or a national level when in reality, these outbreaks are often hyperlocal. And not having a good understanding, when community leaders don’t have a good understanding of the local level of vaccination and community immunity, that’s a significant challenge. So they’re hamstrung without having that data readily available.

[00:42:46]

ELENA RENKEN: Next question here from Fox News. What role does nutrition play in measles severity? Are malnourished children at a higher risk than those who get proper nutrition?

[00:42:57]

TINA TAN: Right. So the recommendation that the WHO made was basically made because there were many children in developing countries that were severely malnourished. And they basically found that by giving doses of vitamin A, it basically decreased the severity of the measles infection. And even here in the United States, the American Academy of Pediatrics and other organizations recommend that individuals here also receive a couple of doses of vitamin A in order to basically help them decrease the potential severity of their measles infection. But as Dr. Higgins brought up before, it is not a treatment or a cure for measles. It is just supportive therapy that can be used.

[00:44:01]

ELENA RENKEN: Thank you. And a broader question here from CNN. Can you shed light on the situation of measles globally? How many outbreaks or cases have we seen in 2025? How many countries are affected? And is this increasing in recent years?

[00:44:19]

AMY WINTER: So measles cases in 2025 globally right now. So the way that other countries, in terms of their surveillance system works, they have sort of joint reporting forms that they aggregate their national levels and they send them up to the WHO. Those cases often take some time to come in, and often they’re delayed. So no, we have not—to my knowledge, the 2025 levels right now are kind of as expected. I will say though, what’s happened prior to 2025 is that we have seen a decline in the MCV, or—I’m sorry, measles-containing vaccine coverage levels. And as a result from 2022 to 2023, we had measles cases that were increased 20% worldwide.

So the estimate—the global estimate in measles cases in 2023 was 10,341,000 cases. Unlike the U.S. where we assume that we’re capturing all cases, internationally, we know that there’s massive underreporting. So we have to get the cases first and do statistical modeling in order to estimate how many infections are actually happening. So yeah, the number of measles cases has increased 20% worldwide from 2022 to 2023. I can’t remember the other question. Sorry, Elena.

[00:45:43]

ELENA RENKEN: Not at all, don’t worry. We’re looking at a few, but I think if anyone has any other context to give on measles globally, any other countries involved, they’re very welcome.

[00:45:54]

DAVID HIGGINS: Well, I think I mentioned this at the beginning, but again, the COVID-19 pandemic caused huge disruptions to measles vaccination around the world. And it’s so important to remember that for Americans, for the United States, measles is only a plane flight away. And so if an American who is unvaccinated goes and travels to one of these countries where anywhere in the world where measles has increased, they bring it back, they’re just a plane flight away. And the disruptions from the pandemic, we have nowhere near caught up yet. And I think we underappreciate here in the United States the degree of measles vaccine disruption around the world. We saw some disruptions here as well from things like changes in health-seeking behavior. There was a while during the pandemic where we asked children not to come in for their well visit. And even when we recommended children to come back in, that was in the first couple of months, there were some families who chose to avoid healthcare settings, to avoid the risk of getting COVID-19. So all of that led to huge disruptions in vaccination around the world. And again, measles is only a plane flight away.

[00:47:09]

TINA TAN: Yeah, and there are countries in Africa and Southeast Asia that the amount of measles being seen has significantly increased. And that is an issue because as Dr. Higgins said, infectious disease is only a plane flight away.

[00:47:31]

ELENA RENKEN: A question here from WGBH News in Boston. Which states, provinces, or countries do you feel are an excellent model for being ready and prepared for a potential outbreak?

[00:47:48]

TINA TAN: So, I mean, I think prior to the outbreaks we’re seeing now, United States really had a very good handle on these outbreaks and were able to respond actually very quickly to get the outbreaks under control. Many other countries abroad, they don’t have the resources that we have to be able to do that. And they don’t have, as Dr. Higgins pointed out, access to the MMR vaccine, which makes it that much more difficult.

[00:48:30]

DAVID HIGGINS: Yeah, that’s a really interesting question because I completely agree. Honestly, the United States was a leader in preparedness for measles, both in our vaccination efforts and in our infrastructure for quickly responding. I think the irony of us having a media briefing on some of the challenges we’re facing here in the United States isn’t lost on any of us. And we need to be actively promoting policies, funding, resources to continue to preserve our ability to prevent and respond to infectious diseases like measles.

[00:49:18]

TINA TAN: Absolutely.

[00:49:22]

ELENA RENKEN: Another question here from Georgia. Does any of you have any information you could share about the costs of measles outbreaks, whether that’s at the individual level when hospitalization is required or the impact on local, state, and federal budgets?

[00:49:39]

DAVID HIGGINS: Well, while others are thinking, I want to highlight a recent study. I believe it was in vaccine, but it was a recent study on the Vaccine for Children Program, the 30 years of the Vaccine for Children Program, right? And in that, they looked at the society level cost savings from measles vaccination in the United States over the past 30 years. $2.7 trillion in societal costs saved. That’s after accounting for the cost of the vaccine and things like that. That is the net benefits to the measles vaccine. And so while that doesn’t answer the individual level, that’s a lot of society savings. So it is absolutely cost effective to vaccinate against measles.

[00:50:28]

TINA TAN: Absolutely, because if you think about someone getting infected and parents having to take off of work to take care of them, or if they have a serious infection and they end up in the hospital, you can imagine that the costs just continue to rise on every single level. And so definitely getting vaccinated is significantly more cost effective.

[00:51:00]

ELENA RENKEN: Question from The Berkshire Eagle in Massachusetts for Dr. Higgins. You mentioned that drops in vaccination rates in a community make it a question, not if, but when there will be an outbreak. How far do vaccination rates need to drop for that to be true?

[00:51:17]

DAVID HIGGINS: Well, so that’s a good question. And I know that we talk about, okay, 95% community immunity is kind of that magic number. And we talk about that number because of how contagious measles is. Like Dr. Tan said at the beginning, up to 18 unvaccinated people who encounter someone with measles can end up getting the disease. But in reality, it is not a light switch. It’s not on or off, right? It’s a sliding scale. And so the more, the better. I get very concerned when I hear about counties or small communities that have 85, 80, 60% vaccination rates or less, right, or even less, because I think, wow, again, you need that spark to light the fire in the community. But when that happens, it’s going to just spread. The wild—it’s going to spread like wildfire through that community when it’s that low.

[00:52:22]

ELENA RENKEN: Thank you. A question here from Verywell Health. Given that the MMR vaccine protects against mumps and rubella as well as measles, are you concerned about outbreaks of those other diseases? And how dangerous are those in comparison with measles?

[00:52:38]

TINA TAN: Measles definitely is the much more severe disease of the three diseases that are prevented by the MMR vaccine.

[00:52:52]

AMY WINTER: Yeah, because measles is the most transmissible of all of them, you could think of measles as a canary in the coal mine in terms of giving us a signal as to the successful or the effectiveness of the vaccination program. So where there is measles, there could be other outbreaks of other infectious diseases, depending on the dearth of a vaccination that may be happening.

[00:53:20]

ELENA RENKEN: A question from an outlet in Boston. I believe Dr. Tan mentioned that one of the complications of measles can be pertussis. Can you explain how those two diseases work together and how does the illness progress to whooping cough?

[00:53:33]

TINA TAN: No, I mean, I didn’t say pertussis. I basically said croup, which is a whooping kind of like harsh cough that people can get, but they don’t get pertussis.

[00:53:46]

ELENA RENKEN: Thank you for clarifying that there. And one more question here from the Summit Daily News in Frisco, Colorado, for Dr. Higgins. A local public health official recently noted in a discussion of measles that we’re a global tourist destination in Colorado. How likely is it that Colorado sees an outbreak or a case of measles in the near future? And what’s Colorado’s vaccination rate for measles? And is that high enough to protect the communities?

[00:54:13]

DAVID HIGGINS: Well, first, I agree, Colorado is a destination rate because we have some beautiful mountains and great skiing just outside of Frisco. So that is obviously a concern, right? And again, I’m going to say it again, it’s only a plane flight away. Pathogens, infectious diseases like measles do not respect borders. And the more travel that we have as we become a more connected world and we have the ability to travel all over the world, which is a good benefit for society, that also means that we are more likely to encounter these things.

In Colorado, our measles vaccination rates, I’m going to specifically highlight our kindergarten measles vaccination rates, they are far below the national median. And they are below 90%. They need to be better. And there are people, including our state health department, including local public health department, that have done a great job over the past couple of years of working to improve our vaccination rates here in Colorado. And in fact, our kindergarten vaccination rate from the prior school year to the most recent school year did actually increase. We were one of the few states where that happened. And I just—it is on the backs of those hardworking public health professionals and community leaders that are working hard to improve uptake.

[00:55:40]

AMY WINTER: Because measles is not endemic in the States, we have to sort of consider three factors, right, when we think about measles outbreak risk. One is what is the pool of susceptibles? How many susceptibles or unvaccinated individuals are there? Two, what is the risk of a new infection entering the population? Three, how clustered are those susceptible populations? We can learn something about what risk may look like this year based on specifically what we saw in 2019. So in 2019, we saw that 63% of the cases that were directly linked to importations were actually from U.S. residents who traveled outside and came back. So it’s not just that it’s foreign travelers who are coming. It’s more than that. It’s U.S. citizens who are traveling outside. Often they’re unvaccinated. They’re getting measles and they’re bringing it back.

The other thing that we learned from the previous outbreaks is that school-aged children are the primary conduit of measles transmission in the country. So focusing certainly on making sure that children are vaccinated, particularly as they’re entering kindergarten, is very important.

[00:56:50]

ELENA RENKEN: Thank you. One more quick question here. What is the mortality rate of measles?

[00:57:00]

AMY WINTER: There’s been a recent published paper, a couple of actually like systematic reviews on the case fatality rate of measles. It differs drastically depending on the populations and the countries. One thing that we’ve found is that the case fatality rate or mortality of measles did decline between 1990 and 2019. This particular paper I’m speaking to estimated the community-based setting 3.03% of individuals under one year old. There was a case fatality rate of 3.03% under one years old, 1.63% one to four, and five to nine at 0.84. That being said, that’s across all countries in the whole entire world. It’s higher in countries where there’s more malnourished children and much, much, much, much, much lower in a place like the U.S. where we have good quality care and healthier children who are not malnutrient. So I don’t know the exact number. In the U.S., we’ve seen 1 death unfortunately recently, but I don’t have the number here.

[00:58:05]

TINA TAN: I mean, normally they say when you think about mortality, it’s 1 to 3 deaths per 1,000 people. That’s what’s usually said.

[00:58:16]

DAVID HIGGINS: And I like to always add when somebody asks that question that we’re concerned with more than just dying from measles, right? We are concerned about the complications, right? And so I have read one in five require hospitalization. It may be even higher than that here in the U.S.. And these are not people and children hospitalized for quarantine measures. They are hospitalized because they’re sick and have a complication. Like Dr. Tan said, they have pneumonia and they need oxygen. They can’t breathe well. Or they have severe diarrhea and they need IV fluids because they can’t stay hydrated. So I like to emphasize that there are a lot of complications that can occur that are also life altering. They might not end up—thankfully, they don’t always end up killing children, but they’re still life altering when a child has to go through that.

[00:59:15]

TINA TAN: Especially if they have seizures or some other neurological deficit or they become deaf or they become blind, then it’s really life altering.

[00:59:27]

ELENA RENKEN: Thank you. Now I have one last question, which we’ll ask our experts here for some quick, crucial takeaways. But first, I want to let reporters on the line know that you’ll receive a brief email survey from us. If you have even just 30 seconds after the briefing ends to let us know your feedback, that would be a huge help to us in designing our programs to be useful to you.

[00:59:48]

ELENA RENKEN: And with that, one final question for our panel. In about 30 seconds, what is one key take-home message for reporters covering measles?

[00:59:59]

TINA TAN: Well, I think measles is a very transmissible viral infection that can affect individuals of all ages. And as we’ve been discussing, it can have some very serious complications that may be permanent that are associated with it. And the best way to protect individuals of all ages against measles is to vaccinate them.

[01:00:34]

DAVID HIGGINS: Yeah, I would say my takeaway is every single case, every hospitalization, every single death from measles is preventable with vaccination. And measles vaccines are safe, which is why most parents—an overwhelming majority of parents say, yes, I’m going to vaccinate my child against measles.

[01:01:01]

AMY WINTER: Yeah, it’s hard to add. Those are definitely the two most important pieces. The measles vaccine is safe, it’s effective, and measles transmission in the United States is driven by failure to vaccinate.

[01:01:14]

ELENA RENKEN: Thank you all so much. We’re so grateful to the scientists here with us today for sharing their knowledge on this urgent topic. And thanks to every journalist on the line for making the effort to get deeper context on this issue to inform your coverage now and in the future. Hopefully we’ll see you all at the next SciLine briefing. Thanks again.