Rising infections expose the consequences of declining immunization rates, misinformation, and weakening public health protections nationwide.
The United States is experiencing its largest measles resurgence in more than three decades, raising alarms among infectious disease experts who warn that declining vaccination rates, persistent misinformation, and gaps in public health infrastructure are allowing one of the world’s most contagious viruses to regain ground. According to the Centers for Disease Control and Prevention (CDC), 2,170 measles cases had been reported as of July 2, the highest annual total in 35 years, with outbreaks spreading across multiple states and affecting both children and adults.
During an American Community Media briefing, leading physicians, epidemiologists and vaccine experts emphasized that the current surge is not the result of changes in the virus itself, but of falling immunization coverage. They argued that measles, once eliminated from endemic transmission in the United States in 2000, has found new opportunities to spread as communities fail to maintain the vaccination levels needed for herd immunity.
Patsy Stinchfield, pediatric nurse practitioner and executive director of the Measles Collaborative, stressed that measles has not become more dangerous over time. Instead, she said, communities have become more vulnerable by allowing vaccination rates to decline.
“The virus hasn’t changed. Our vaccine coverage has,” Stinchfield said, explaining that measles requires approximately 95% vaccination coverage to prevent sustained transmission. Once immunization rates fall below that threshold, even by a few percentage points, outbreaks can expand rapidly because a single infected individual may transmit the virus to as many as 18 others.
She also clarified a common misconception surrounding the country’s previous success against the disease. While the United States declared measles eliminated in 2000, meaning continuous domestic transmission had been interrupted, the virus was never eradicated globally. As long as measles circulates elsewhere in the world, imported cases remain inevitable, making high vaccination coverage essential to preventing new outbreaks.
Declining vaccination rates fuel expanding outbreaks
Experts pointed to several regions where declining immunization has created favorable conditions for measles transmission.
In Utah, where the state has battled a year-long outbreak, fewer than 84% of children have received both recommended doses of the MMR vaccine. Dr. Andrew Pavia, chief of Pediatric Infectious Diseases at the University of Utah, explained that while statewide vaccination rates appear relatively high, localized communities with significantly lower coverage became the epicenter of sustained transmission.
According to Pavia, some communities along the Utah-Arizona border recorded vaccination rates as low as 30% to 40%, influenced by religious opposition to vaccines, distrust of government institutions, and broader anti-vaccination sentiment. Once measles entered these communities, it quickly spread throughout the state.
Pavia also warned that official case counts likely underestimate the true scale of the outbreak. Because many infected families never seek laboratory confirmation, researchers developed epidemiological and genomic models suggesting actual infections may be two to four times higher than reported. In Utah alone, an official total of roughly 700 cases could represent between 1,400 and 2,800 infections.
The growing number of adult cases is another emerging concern. Nearly one-quarter of all measles infections nationwide this year have occurred in adults over 20 years old, many of whom have never encountered the disease during their medical careers or personal lives. Adults, along with children under five, face a greater risk of hospitalization and severe complications.
Pregnant women represent another particularly vulnerable group. Pavia noted that measles infection late in pregnancy can be transmitted to newborns either before or immediately after birth, potentially resulting in life-threatening illness.
Misinformation continues undermining vaccination efforts
Health experts repeatedly identified misinformation as one of the principal drivers behind declining vaccination rates.
Stinchfield described years of outreach within Minnesota’s Somali community, where anti-vaccine activists falsely claimed that the MMR vaccine causes autism. Before these campaigns gained traction, vaccination rates among Somali children exceeded 90%. As misinformation spread, many parents delayed vaccination until children reached school age, leaving toddlers unprotected during their most vulnerable years.
The resulting decline contributed to repeated outbreaks, including one in 2017 that primarily affected Somali preschoolers and another resurgence in 2024. Stinchfield said rebuilding trust has required close collaboration with Somali healthcare workers, religious leaders, community organizations and parents themselves.
Rather than repeatedly debunking myths, she said public health officials increasingly focus on explaining both the real dangers of measles and the extensive scientific evidence supporting vaccine safety. She also emphasized educating families about autism itself, noting that decades of research have found no connection between autism and the MMR vaccine.
Dr. Benjamin Neuman, professor of biology at Texas A&M University, reinforced that message by explaining that the current MMR vaccine remains highly effective despite being developed decades ago. Unlike influenza or COVID-19, measles mutates slowly, allowing vaccines based on strains isolated in the 1950s to continue providing long-lasting protection against modern variants.
He explained that while the virus continues to evolve, the components recognized by the immune system have changed very little over time, making widespread vaccine updates unnecessary.
Public health challenges extend beyond vaccination
Speakers also warned that controlling outbreaks has become increasingly difficult because of broader pressures on public health systems.
Pavia said reduced public health funding has limited the ability of local agencies to conduct case investigations, contact tracing and community outreach, all of which are critical to containing highly contagious diseases like measles.
At the same time, healthcare providers face an unusual challenge: many younger physicians have never treated measles because the disease had become so rare in the United States. This lack of firsthand clinical experience can complicate early recognition and diagnosis.
Dr. Jose Romero, former director of the CDC’s National Center for Immunization and Respiratory Diseases, also raised concerns about declining public confidence in vaccines and the potential consequences for immigrant and underserved communities.
He warned that continued erosion of vaccination rates could lead not only to more measles outbreaks but also to the return of diseases that many physicians rarely encounter today, including bacterial meningitis and other vaccine-preventable illnesses. Romero emphasized that misinformation, combined with reduced outreach to vulnerable populations, threatens decades of public health progress.
The panel also discussed how fear surrounding immigration enforcement may discourage some families from seeking medical care, delaying both diagnosis and vaccination while allowing outbreaks to spread further.
Despite addressing numerous scientific and policy issues, all four experts concluded with the same message: measles remains one of the most preventable infectious diseases, provided communities maintain high vaccination coverage. They urged families to verify their immunization records, ensure children receive both recommended doses of the MMR vaccine, and rely on evidence-based medical guidance rather than misinformation circulating online.