The U.S. Measles Outbreak Is a Wake-Up Call for Public Health

The United States is facing its worst measles outbreak in more than 30 years with 1,288 confirmed cases across 38 states, including the tragic deaths of three people, two of them school-aged children. This surge, fueled almost entirely by unvaccinated individuals, is not just a numbers problem. It’s a warning that the foundation of our public health infrastructure, routine vaccination, is under threat.

This outbreak matters. Not just because of its scale, but because of what it signals about the growing cracks in our collective immunity. There are three urgent reasons why this measles resurgence should concern all of us:

1. We’re at risk of losing our measles elimination status.

The United States declared measles eliminated in 2000, a remarkable achievement made possible by a safe, highly effective vaccine and decades of public health investment. But that status depends on no sustained community transmission for over 12 months. With Texas reporting 753 cases this year alone and ongoing spread across multiple states, we are dangerously close to losing that designation. Losing elimination status would mark a major public health setback and it would signal to the world that the U.S. is no longer leading in vaccine-preventable disease control.

2. We are now seeing sustained community transmission and that changes everything.

Outbreaks are no longer isolated to small clusters. With at least 27 outbreaks this year, and 88% of cases linked to these clusters, we're seeing sustained transmission that threatens regional, national and international health. Once measles becomes embedded in communities with low vaccination rates, it spreads fast, the virus is one of the most contagious on the planet, capable of infecting 9 out of 10 unvaccinated people who are exposed. This is not theoretical: deaths are already occurring. And unless we act swiftly, more will follow.

3. Low community-level vaccination rates are breaking herd immunity.

National averages can be deceiving. While the CDC reports around 93% MMR vaccination coverage, herd immunity against measles requires 95% or more. In many counties, vaccination rates are well below that threshold, creating fertile ground for outbreaks. Nearly 280,000 kindergarteners are not fully vaccinated during the 2023-2024 school year. That’s not just a statistic, it’s a vulnerability, especially for infants too young to be vaccinated and immunocompromised individuals who rely on community protection.

Let’s be clear: measles is not a mild illness. It can lead to pneumonia, brain swelling, and death. The MMR vaccine is 97% effective with two doses, a tool we’re simply not using to its full potential.

Public health is not just a set of recommendations; it’s a social contract. When that contract frays, we all suffer. We must rebuild trust, fight misinformation, and recommit to high vaccination coverage across all communities.

Originally published by the Harvard Kennedy School Belfer Center for Science and International Affairs here.