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Updated March 31, 2025.
The Centers for Disease Control and Prevention (CDC) has issued a health advisory warning about the spread of measles in multiple states across the country. As of March 28, the officials have confirmed over 500 cases of measles including in Washington, D.C. and Maryland, as well as the death of a child in Texas. Reports show that an estimated 94% of measles infections are among individuals who are unvaccinated, or whose vaccination status could not be confirmed. Roughly 80% of cases are in children and adolescents (ages under 5 – 19 years).
Amid confusion and growing concern, Amira Roess, an epidemiologist and professor of global health, clarifies the benefits of vaccinating children and adolescents against measles. Roess is an expert on emerging zoonotic (animal to human) infectious diseases and their risk factors. She has led the Pew Policy Commission on Industrial Food Animal Production as the science director, served as a CDC epidemic intelligence service officer, and provided guidance for preparedness and response to H5N1 bird flu in 2006. Roess was a leading source during the COVID-19 pandemic and is an in-demand public health consultant.
Wasn’t measles eradicated in the United States?
It’s important to understand the difference between elimination and eradication when it comes to infectious diseases. When we say we have eliminated a virus that means that there is no ongoing transmission among people in a defined geographic area, such as the U.S. Eradicated means the virus (or any other disease-causing agent) is no longer infecting people anywhere in the world. The only virus that has been eradicated is the smallpox virus which was declared eradicated in 1980.
Smallpox is considered eradicated because we have not seen a single naturally occurring case of smallpox since 1977 anywhere in the world. Once it was eradicated from the globe it was possible to discontinue smallpox vaccination because there was no longer a risk of transmission.
Each country works to eliminate the disease. If every country in the world is successful and no disease transmission is reported for at least one year, then that means the pathogen that causes the disease has been eradicated.
This is not the case for measles. Measles had been declared eliminated in the U.S. in 2000. Since then, there have been localized outbreaks in small tight-knit groups, such as the community in West Texas. This is largely due to low vaccination rates in these communities. Measles is nowhere near eradicated. In 2023, there was about an 80% increase in cases globally, which is a likely contributor to the cases popping up in 2024.
Why is the measles vaccine still recommended?
Measles is one of the most infectious viruses out there and can stay suspended in the air for more than two hours, infecting people more easily than most other viruses. A big problem right now is that in some small communities the measles vaccination rate is below the recommended target and these communities are at risk for outbreaks, severe illness and even death. This is one of the reasons that it is important that we work together to get our vaccine rates up.
Remember that if an outbreak emerges in one part of the country or one part of the world it can be a matter of days or hours before cases pop up in other parts of the country or world. This is because of domestic and international travel and trade that are a part of modern life.
In addition to the large outbreak that started in West Texas, there are multiple measles outbreaks in the U.S. currently, including in Washington, D.C., Maryland, and Virginia, and many of these outbreaks have been linked to international travel. These outbreaks all show us that the risk of transmission is still present which is why measles vaccination is important.
Why should I vaccinate my child against measles?
Measles is largely preventable. Just like we wear seatbelts to prevent severe injury and death if we were to get into a car accident, we use vaccines to prevent illness and death if we were to get exposed to measles and other infectious diseases. In the U.S. about 93% of school-aged children received the measles vaccine and the overwhelming majority of parents see the benefit of measles vaccination.
According to the CDC, the measles vaccine is proven to be safe and effective. Over 90% of parents choose to vaccinate their children against measles, which is similar to choosing to use seatbelts to protect children.
What is the MMR vaccine and why is it recommended by my child’s pediatrician?
The MMR vaccine contains a combination of measles, mumps, and rubella vaccines, providing immunization from all three. It is one of the oldest and safest vaccines we have. It consistently decreases illness and death and is used around the world and most communities in the U.S.
Do adults need to be vaccinated against measles?
If you received the MMR vaccine as a child, you most likely do not need to receive another shot as an adult. Those who weren’t vaccinated as children should do so as soon as possible. The MMR vaccine is a two-dose vaccine and is generally sufficient but consult with your health care provider to be sure. Also, if you are immunocompromised or work in certain professions you may need a booster.
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MEDIA INQUIRIES: For reporters who wish to speak to Amira Roess about measles or other emerging diseases, please email media contact Michelle Thompson at mthomp7@gmu.edu.
Amira Roess is a professor of global health and epidemiology at George Mason University's College of Public Health, Department of Global and Community Health. She is an epidemiologist with expertise in infectious diseases epidemiology, multidisciplinary and multi-species field research and evaluating interventions to reduce the transmission and impact of infectious diseases. Roess currently oversees several longitudinal studies to understand emergence and transmission of zoonotic infectious diseases globally, including the emergence and transmission of Campylobacter (with support from The Bill and Melinda Gates Foundation), MERS-CoV (with support from the U.S. National Science Foundation), and the development of the microbiome during the first year of life. She studies links between food animal production and emerging infectious and zoonotic diseases emergence globally, and mHealth (especially apps) technology integration and evaluations to reduce the impact of infectious disease outbreaks, promote health care, and help reduce disparities.
About George Mason University
George Mason University is Virginia’s largest public research university. Located near Washington, D.C., Mason enrolls more than 40,000 students from 130 countries and all 50 states. Mason has grown rapidly over the past half-century and is recognized for its innovation and entrepreneurship, remarkable diversity, and commitment to accessibility. In 2023, the university launched Mason Now: Power the Possible, a one-billion-dollar comprehensive campaign to support student success, research, innovation, community, and stewardship. Learn more at gmu.edu.
About College of Public Health at George Mason University
The College of Public Health at George Mason University is the first College of Public Health in Virginia and a national leader in inclusive, interprofessional, public health research, education, and practice. The college is comprised of public health disciplines, health administration and policy, informatics, nursing, nutrition, and social work. The college offers a distinct array of degrees to support research and training of professionals dedicated to ensuring health and well-being for all. The college’s transdisciplinary research seeks to understand the many factors that influence the public’s health and well-being throughout the lifespan.
The college enrolls more than 1,900 undergraduate and 1,300 graduate students in our nationally recognized programs, including 5 undergraduate degrees, 7 master’s degrees, and 4 doctoral degrees, and 10 certificate programs. Our graduates are uniquely prepared to thrive in an increasingly multicultural, multidisciplinary, community-focused public health landscape.