Measles Resurgence and the Fragility of Herd Immunity: Implications for Pediatric Infectious Disease Practice

Summary

Reduced vaccine coverage has led to a resurgence of vaccine-preventable diseases, threatening decades of public health progress. This perspective explores the rise in measles cases and outlines how the pediatric infectious disease community can rebuild vaccine confidence to reverse this trend.

INTRODUCTION

Vaccines are a cornerstone of modern public health, having saved 154 million lives globally over 50 years—averaging 6 lives per minute. However, decades of progress are at risk as vaccine-preventable diseases re-emerge. In this perspective, we examine measles resurgence, analyze drivers of declining vaccine coverage, and outline how pediatric infectious disease (ID) clinicians and researchers can strengthen vaccine uptake and safeguard public health.

FROM A FORGOTTEN COMPLICATION TO A MODERN TRAGEDY

In April 2025, the pediatric ID service at a Connecticut hospital evaluated a 6-year-old boy hospitalized with new-onset myoclonic movements of his upper extremities. The clinical picture was concerning, but diagnosis remained elusive until review of medical records showed he had contracted measles at age one while abroad. Workup revealed elevated measles-specific antibodies in serum and cerebrospinal fluid. He had a rapid decline in neurologic and functional status, consistent with Subacute Sclerosing Panencephalitis (SSPE), a rare but almost always fatal complication of measles infection.

While Connecticut’s ID team managed the devastating SSPE case, public health officials elsewhere addressed the largest measles outbreak in 3 decades. On April 6, 2025, Texas officials reported the year’s second measles death, involving 2 healthy school-aged children who developed severe measles pneumonia. The widespread outbreak in Texas underscores how rapidly measles can spread when exemption rates compromise herd immunity. These cases are not anomalies but expected outcomes when measles spreads in under-vaccinated communities.

MEASLES EPIDEMIOLOGY AND THE FRAGILITY OF HERD IMMUNITY

Measles is an acute viral illness with fever, cough, coryza, conjunctivitis, and a descending maculopapular rash. Most children recover; however, complications like pneumonia, keratitis, and encephalitis occur.

Since the measles vaccine’s 1963 introduction, it has been a successful public health intervention. Global incidence and mortality declined sharply with its use, and endemic transmission was eliminated in the United States by 2000.¹ The live attenuated vaccine is highly effective, with 2 doses achieving seroconversion in nearly all recipients. However, because measles is highly contagious, herd immunity is fragile; even small declines in coverage can increase the risk of large-scale outbreaks when the virus is reintroduced.

Recent US measles outbreaks highlight ongoing challenges in sustained control and the need for high immunization rates to prevent ongoing transmission (Figure 1). In 2014, 667 US cases were mainly due to an outbreak after unvaccinated Amish missionaries brought measles from the Philippines.³ Similar imported cases with local transmission occurred in a 2017 Minnesota outbreak among Somali Americans and 2018-2019 outbreaks in New York’s Orthodox Jewish communities.³ The ongoing 2025 multistate outbreak shows the threat of declining immunization. As of September 23, 2025, the United States has reported 1514 confirmed measles cases across 42 jurisdictions, the highest number since 1992. More than 86% of cases were outbreak-associated, over 92% occurred in unvaccinated individuals, 32% required hospitalization—half of whom were children under 5—and 3 measles-associated deaths have been documented.² These outbreaks should serve as alarm bells for the IDs community, compelling us to address both the resurgence of vaccine-preventable diseases and factors enabling their return. Our goal must be to foster a culture that recognizes vaccines as scientific achievements, views vaccination as a gift of health, and prioritizes public trust. This requires coordinated efforts across research, education, legislation, advocacy, equity, economics, and service delivery (Figure 2).

Figure 1.

Confirmed Measles Cases Reported in 2025 and MMR Vaccine Coverage, United States.

Footnote: Map includes measles cases reported between January 1 and August 1, 2025, with circle size proportional to case counts. Estimated measles-mumps-rubella (MMR) vaccination coverage among kindergarten-aged children during the 2023-2024 school year is displayed at the county level for Texas and at the state level for all other states, based on the most granular available data. Regions with lower kindergarten MMR coverage often coincide with higher reported measles incidence. Data sources: Centers for Disease Control and Prevention; Johns Hopkins University measles tracking team.

Figure 2.

Framework for Strengthening Public Confidence in Vaccination. Framework illustrating 6 domains: Education, research, service delivery, equity and economics, advocacy, and legislation that collectively strengthen public confidence in vaccination by fostering trust. Strategies include communication, clinical pathways, economic support, community engagement, and policy measures, providing a comprehensive approach to promote vaccine acceptance and counter disinformation.

UNDERSTANDING THE DECLINE IN VACCINE COVERAGE

The global decline in vaccination coverage is a growing public health concern. Vaccine hesitancy is multifactorial, with diminished public trust being the most important driver.³ This erosion in confidence stems partly from a discredited 1998 publication by Andrew Wakefield that falsely linked MMR vaccine to autism. Although the study was retracted and refuted, the doubts persist. Distrust has intensified through misinformation and anti-vaccine narratives on social media.⁴ These messages are amplified by commercial interests, including the trillion-dollar wellness industry, whose interests align with promoting alternative health products. The politicization of public health has reframed vaccination from an evidence-based intervention into a signal of political identity, undermining vaccine uptake initiatives.

Complacency from successful vaccination programs can contribute to lower uptake. As diseases like measles become rarer, people may focus less on infection risks and more on perceived vaccination risks. This causes caregivers to underestimate real dangers. Additionally, pediatric vaccines are often given as combinations protecting against several diseases. If caregivers decline vaccination against 1 disease, children may become vulnerable to others.

Structural and logistical barriers play a key role in underserved areas. Studies show how immunization decisions are influenced by clinic access and finances. Missed opportunities, such as misunderstanding contraindications or not offering vaccines, lead to lower coverage. These issues worsen due to policies creating systemic weaknesses. While states mandate vaccinations for school entry, provisions allowing non-medical exemptions for religious or philosophical reasons have created under-immunization pockets. Nationwide, vaccine exemptions are rising, with 14 states reporting exemption rates of over 5%.⁵ In contrast to states that have tightened requirements, Florida has advanced plans to remove its vaccination mandate for school entry, a policy shift expected to further depress coverage and heighten outbreak vulnerability. Because measles requires vaccination coverage above 90%-95% to prevent transmission, even a 5% exemption rate can undermine herd immunity and enable outbreaks of this highly contagious virus. In fact, these exemptions have been associated with increased outbreak risk.⁶ After major outbreaks, California and New York eliminated non-medical exemptions, resulting in significant vaccine coverage increases.⁷ However, mandates alone won’t suffice. Sustained change requires rebuilding community trust and improving public health communication.

THE COST OF VACCINE HESITANCY

Declining vaccination coverage consequences are evident. Models developed before the current US measles resurgence indicate that routine childhood vaccination rates could fall by 25%, leading to measles becoming endemic again within 5-10 years.⁸ Over 25 years, this scenario is projected to cause 27 million measles cases, 87 600 poliomyelitis cases, 790 rubella cases, and over 80 000 deaths from these and other vaccine-preventable diseases.⁸ These declines in vaccine uptake undermine decades of progress and require action from clinicians, public health experts, and policymakers.

THE ROLE OF PEDIATRIC INFECTIOUS DISEASE SPECIALISTS AND THE PATH FORWARD

Pediatric ID specialists are vital in rebuilding vaccine trust. We have seen the severe harm these infections cause. Cases like our patient with SSPE show the potential implications of these vaccine-preventable illnesses when vaccination rates decline. Sharing firsthand accounts of severe illness, such as SSPE or measles-related pneumonia, helps families understand the risks of vaccine-preventable diseases, moving beyond statistics to real impact on children’s lives. Pediatric ID clinicians should review immunization status and address missed opportunities at each encounter, ensuring vaccination whenever possible in inpatient and consult settings. By integrating immunization checks into clinical workflows, including admissions, consults, and discharges, ID specialists can reduce missed vaccination opportunities and improve coverage.

We must confront the reality that public trust will not be rebuilt overnight and prepare for the reemergence of vaccine-preventable diseases. While these diseases will impact many specialties, pediatric ID clinicians are at the forefront, uniquely positioned to lead in clinical care and public health advocacy. The success of vaccination has left today’s workforce without firsthand experience in diagnosing these illnesses. Therefore, we must rebuild institutional knowledge and preparedness to ensure health systems can effectively respond to these returning threats.

Our influence must extend beyond hospital walls. Pediatric ID specialists shape immunization policy, engage in public discourse, and equip future clinicians with evidence-based communication skills. By collaborating with local pediatricians and advocating for evidence-based policies—such as limiting non-medical exemptions and improving vaccine access—ID specialists can influence immunization rates and community protection.

Sustained advocacy paired with transparent communication helps rebuild community trust. Rather than relying on myth-busting, pediatric ID specialists should adopt empathetic conversations that acknowledge parental concerns and share experience with vaccine-preventable diseases. Motivational interviewing techniques have proven effective in fostering trust and guiding families toward vaccination decisions; these approaches build trust and measurably improve vaccine acceptance among hesitant families. Abstaining from public discourse today, especially on social media where misinformation thrives, cedes authority to those undermining science and public health policy. By participating visibly, we can counter falsehoods, share credible evidence, and amplify messages that protect children’s health.

Our perspective must be global. Protecting children abroad prevents outbreaks at home. Every measles case in the United States in 2025 will be due to viruses brought by international travelers or spread from viruses brought into the United States. Supporting international immunization programs, such as Gavi, the Global Alliance for Vaccines and Immunization, which has helped immunize over a billion children in 78 low-income countries, is not just foreign aid but a strategic investment in domestic health security. There is no better example than the smallpox eradication campaign. Studies show that the United States recoups its investment in public health eradication efforts every 26 days, making it one of the most cost-effective public health investments in history.

Reversing vaccine hesitancy demands sustained engagement—and we are uniquely positioned to lead. As pediatric ID clinicians, we are trusted messengers, skilled educators, and advocates for children’s health. By sharing expertise, building partnerships, and modeling evidence-based communication, we can restore confidence in vaccines and protect future generations. Now is the time to lead by example and ensure every child benefits from immunization. It is time to act, not just in the clinic, but as leaders, demonstrating that together we can restore trust and secure a healthier future for all children.

Funding

None declared.

Conflicts of interest

None declared.

Data availability

None declared.