Genotypes, Clusters, and Consequences: The Epidemiology of the New Measles Wave

Abstract

The United States, once a global exemplar for measles elimination, currently faces its most precarious public health challenge regarding the virus in a quarter-century. Following the declaration of elimination in 2000, the maintenance of this status has relied heavily on robust herd immunity and effective surveillance. However, the epidemiological data from 2025 through early January 2026 reveals a systemic erosion of these defenses. With confirmed case counts exceeding 2,000, the re-emergence of measles-associated mortality, and the establishment of prolonged transmission chains, the nation stands on the verge of losing its elimination status. This report provides an exhaustive examination of the current crisis, analyzing the molecular epidemiology of the dominant Genotype D8 and B3 strains, the clinical burden of disease including the looming threat of Subacute Sclerosing Panencephalitis (SSPE), and the sociological drivers of vaccine hesitancy that have facilitated these outbreaks. Through detailed case studies of major clusters in West Texas, the Utah-Arizona border, and South Carolina, this analysis underscores the urgent necessity for a recalibrated public health response to prevent the re-establishment of endemic measles.

1. Introduction: The Fragility of Measles Elimination

1.1 The Historical Achievement and Its Erosion

In the annals of public health, the elimination of measles in the United States in 2000 stands as a monumental achievement. Defined by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) as the absence of continuous disease transmission for 12 months or more in a specific geographic area, elimination signified the triumph of the two-dose Measles-Mumps-Rubella (MMR) vaccination program.¹ For decades, this status meant that while the virus was occasionally imported by travelers from endemic regions, it failed to find a foothold in the U.S. population sufficient to sustain year-round circulation. The virus would spark small, self-limiting fires that were quickly extinguished by the "firewall" of herd immunity.

However, the events of 2025 have fundamentally altered this dynamic. The firewall has developed fissures. Unlike previous years, where outbreaks were discrete events, 2025 witnessed the coalescence of importation events into sustained transmission chains that have persisted for nearly a full calendar year. The psychological and policy complacency that often accompanies long-term public health success has collided with a post-pandemic sociological shift in vaccine attitudes, creating a fertile ground for the resurgence of one of the most contagious human pathogens known.³

1.2 The 2025 Resurgence: A Statistical Overview

The year 2025 concluded with an epidemiological profile that mirrors the pre-elimination era in its intensity, if not yet its total volume. CDC surveillance data confirms a total of 2,065 measles cases reported across 44 jurisdictions.⁵ To contextualize the magnitude of this resurgence, this figure represents a nearly tenfold increase over the 285 cases reported in 2024 and significantly exceeds the 1,274 cases from the notable 2019 outbreak year.⁵

The resurgence was not characterized by sporadic, unrelated cases but rather by efficient community transmission. Of the 2,065 confirmed cases, 1,820 (88%) were associated with 49 distinct outbreaks.⁵ This high percentage of outbreak-associated cases indicates that the virus is not merely being imported but is actively circulating within U.S. communities. Furthermore, the resurgence has re-introduced measles mortality to the American landscape. Three confirmed deaths—two pediatric and one adult—were recorded in 2025, marking the first such fatalities in a decade and shattering the misconception that measles is a benign rite of passage.¹

1.3 The Looming Deadline: January 2026

As of January 3, 2026, the United States faces a critical deadline. The WHO criteria for elimination require that no single strain of the virus circulate continuously for more than 12 months. Genomic surveillance has identified a specific lineage of Genotype D8 (sequence 9171) that has been responsible for the massive outbreak in West Texas since January 2025.² If this transmission chain is not proven to be broken by late January 2026, the United States will technically meet the definition of having re-established endemic measles.² This potential loss of status is not merely a bureaucratic reclassification; it represents a fundamental failure of the public health infrastructure to protect the population from a vaccine-preventable disease.

2. The Biology of Transmission and Susceptibility

2.1 The Viral Engine: R0 and Aerosolization

To understand the rapid expansion of outbreaks in 2025, one must appreciate the biological capabilities of the measles virus (MeV). Measles is an airborne pathogen with a basic reproduction number (R_0) historically estimated between 12 and 18, meaning a single infected individual in a susceptible population can infect up to 18 others.⁹ However, recent modeling suggests that in specific environments—such as poorly ventilated indoor spaces or close-knit communal gatherings—the effective transmission rate can be even higher.

The virus is transmitted via respiratory droplets that can remain suspended in the air and infectious for up to two hours after an infected person has left the area.¹⁰ This "memory" of the air allows for transmission without direct face-to-face contact. In the outbreaks observed in 2025, particularly in high-density living situations or crowded school environments, this aerosolization capability allowed the virus to exploit even narrow gaps in vaccination coverage.¹¹

2.2 The Susceptible Cohort

The primary fuel for the 2025 epidemics was a growing cohort of susceptible individuals. Surveillance data indicates that 93% of the confirmed cases in 2025 occurred in individuals who were unvaccinated or had an unknown vaccination status.⁵ This creates a stark dichotomy in the population: a highly protected majority and a highly vulnerable minority that is clustered geographically and socially. When the virus enters these "pockets" of susceptibility—such as the Mennonite communities in Texas or the FLDS communities on the Utah-Arizona border—the local herd immunity is effectively zero, allowing the virus to spread with pandemic-like efficiency.¹²

3. National Epidemiological Profile (2025-2026)

3.1 Aggregate Case Data and Trends

The trajectory of the 2025 measles year was defined by a relentless accumulation of cases. While the early months of 2024 saw manageable numbers, the curve for 2025 accelerated sharply in January and maintained a high plateau throughout the year. By the end of December 2025, the case count had reached 2,065.⁵

Table 1: National Measles Surveillance Summary (2024 vs. 2025)

Metric	2024 Statistics	2025 Statistics	% Change / Difference
Total Confirmed Cases	285	2,065	+624%
Total Reported Outbreaks	16	49	+206%
Outbreak-Associated Cases	198 (69%)	1,820 (88%)	+19% (proportion)
Hospitalizations	N/A	235 (11%)	Significant Burden
Deaths	0	3	Re-emergence of Mortality
Jurisdictions Affected	32	44	Expanded Geographic Scope

Data aggregated from CDC Surveillance Reports and MMWR.¹

The shift from 69% outbreak-associated cases in 2024 to 88% in 2025 is statistically significant. It suggests a move away from "dead-end" importations—where a traveler returns home and infects perhaps one or two family members before the chain stops—toward "sustained community transmission," where the virus jumps from household to household and institution to institution.⁵

3.2 Geographic Distribution and Hotspots

The geographic footprint of measles in 2025 was broad, affecting 44 jurisdictions, but the intensity was highly concentrated. A heatmap of the outbreak would show intense "red zones" in the Southwest, the Midwest, and the Southeast, driven by specific localized outbreaks.⁵

• The Southwest Corridor: Texas, New Mexico, and Arizona formed a contiguous block of high transmission. Texas alone reported over 654 cases associated with the West Texas outbreak, while Arizona reported 196 cases, heavily linked to the outbreak on its northern border with Utah.¹

• The Upper Midwest: Minnesota and Illinois experienced significant clusters, with 52 cases in the Twin Cities and 57 in Chicago, respectively.¹⁴ These outbreaks in urban centers highlight the risk of density in facilitating spread.

• The Southeast: South Carolina emerged as a late-year epicenter, with 188 total cases by January 2, 2026, primarily in the Upstate region.¹⁵

3.3 Demographic Vulnerability

The age distribution of the 2025 cases reinforces the classic understanding of measles as a pediatric threat, but with notable deviations.

Table 2: Age Distribution and Hospitalization Rates (2025)

Age Group	Number of Cases	% of Total Cases	Hospitalizations	Hospitalization Rate (%)
< 5 Years	537	26%	105	20%
5–19 Years	865	42%	53	6%
20+ Years	650	31%	77	12%
Unknown	13	1%	0	0%
Total	2,065	100%	235	11%

Source: CDC Data.⁵

The data reveals two critical insights. First, the highest raw number of cases (865) occurred in school-aged children (5-19 years), reflecting the role of schools as amplification nodes in communities with high exemption rates. Second, the highest severity was seen in the youngest cohort. Children under 5 years old were hospitalized at a rate of 20%, nearly double the national average.⁵ This group includes infants too young to be vaccinated, who rely entirely on the community's herd immunity for protection.

4. Molecular Epidemiology: The Story in the Sequences

Advanced molecular surveillance has been pivotal in tracking the 2025 resurgence. By sequencing the viral genome from patient samples, the CDC and state laboratories have been able to map the transmission pathways and identify the origins of the outbreaks.

4.1 The Dominance of Genotype D8

The vast majority of measles cases in the U.S. in 2025 were caused by Genotype D8. In a representative analysis of 208 specimens from the West Texas outbreak and its satellite clusters in Kansas and New Mexico, 100% were identified as Genotype D8.¹

More specifically, 94% of these sequences shared an identical "N-450" sequence (distinct sequence ID 9171). This genetic uniformity is the molecular signature of a single introduction event followed by explosive, sustained growth. It confirms that the hundreds of cases across these states were not independent importations from abroad but were part of a massive, interconnected web of domestic transmission originating from the initial West Texas introduction in January 2025.¹

4.2 Genotype B3: The Global Signal

While D8 dominated the landscape, Genotype B3 also maintained a presence, accounting for approximately 10% of characterized cases.¹ Unlike the monolithic D8 cluster, the B3 sequences showed greater diversity, with five distinct sequences identified across states like Alaska, California, Florida, and New York.¹⁶

This diversity suggests multiple separate importation events. Genotype B3 is endemic in many parts of the world, particularly the African and Eastern Mediterranean regions. Its continued detection in the U.S. serves as a reminder that as long as measles circulates globally, the U.S. border remains permeable to the virus. However, broadly speaking, the B3 importations in 2025 did not result in the same catastrophic "super-spreader" events as the D8 introduction in Texas.¹⁸

5. Anatomy of Major Outbreaks: Case Studies in Vulnerability

The 49 outbreaks of 2025 were not uniform. They varied in setting, size, and sociological context. Three major clusters define the year's epidemiological narrative.

5.1 Case Study 1: The West Texas "Anchor"

The most consequential outbreak of the year began in January 2025 in Gaines County, Texas.¹² This outbreak is historically significant because it likely serves as the "anchor" event that may cost the U.S. its elimination status.

• Community Dynamics: The outbreak centered on a close-knit Mennonite community. This demographic is characterized by large family sizes, frequent communal worship and social gatherings, and historically lower rates of vaccination, often due to a mix of religious conviction and skepticism of state mandates.²⁰

• Transmission Velocity: The virus spread rapidly through this network. By April 2025, the outbreak accounted for 82% of all measles cases reported in the U.S. up to that point.¹ The attack rate was fueled by the high density of social interactions, typical of such insular communities.

• Geographic Spillover: The outbreak did not respect state lines. It seeded 63 cases in four New Mexico counties and seven cases in Oklahoma.¹ Furthermore, it had international repercussions; a resident of Mexico traveled to Gaines County, contracted the virus, and initiated a subsequent outbreak in Chihuahua, Mexico.¹ This demonstrates how a domestic U.S. outbreak can become an exporter of disease, reversing the traditional "importation" narrative.

• Mortality: This outbreak cluster was responsible for the two pediatric deaths reported in Texas—a 6-year-old and an 8-year-old, both unvaccinated.²¹

5.2 Case Study 2: The Utah-Arizona Border Crisis

In late 2025, a severe outbreak emerged in the "Short Creek" region, which encompasses the twin towns of Hildale, Utah, and Colorado City, Arizona.

• The Outbreak Scale: As of late December 2025, the cluster had grown to 254 cases, making it the second-largest of the year.²² Arizona's state total of 196 cases was largely driven by this single event.⁵

• Vulnerable Populations: The outbreak was particularly dangerous for infants. Reports indicated that as many as 11 babies were exposed in Utah settings.²³ Given the 1-in-600 risk of SSPE for infants (discussed in Section 6.3), this exposure is of grave long-term concern.

• Sociological Context: Similar to West Texas, this region has a history of distrust toward government intervention, partly rooted in the history of the FLDS church. This skepticism complicates contact tracing and vaccination campaigns, allowing the virus to circulate largely unchecked until it burns through the susceptible population.¹³

5.3 Case Study 3: The South Carolina Surge

While the Texas and Southwest outbreaks dominated the first half of the year, South Carolina became a primary theater of transmission in the fourth quarter of 2025.

• Chronology of Escalation:

• July 9: First confirmed case in the Upstate region.

• October 2: DPH officially declares an outbreak after a cluster of cases with no known source is identified, indicating community spread.¹⁵

• December 30: Case count jumps to 176.

• January 2, 2026: Total reaches 188 cases, with 185 linked to the single Spartanburg County cluster.¹⁵

• The "School Effect": The outbreak was heavily amplified by schools. Detailed immunization reports from South Carolina reveal that while some schools maintain high coverage, others have slipped. For example, while Abbeville High reported 97.66% immunization, private institutions in the region showed alarming gaps, with some reporting rates as low as 30% or 46%.¹⁵

• Quarantine Impact: The public health response required the quarantine of 223 individuals by early January 2026. This mass quarantine disrupts education and economic productivity, illustrating the wider societal cost of the outbreak beyond immediate health outcomes.¹⁵

6. Morbidity, Mortality, and Long-Term Sequelae

The 2025 data rigorously refutes the modern misconception that measles is a mild, inconsequential illness. The clinical reality observed in U.S. hospitals was one of severe acute illness and tragic mortality.

6.1 Acute Clinical Burden

The overall hospitalization rate for the 2,065 cases was 11%.⁵ However, this average dilutes the severity seen in specific groups.

• Pediatric Hospitalization: For children under 5, the hospitalization rate was 20%.⁵ One in five infected young children required inpatient care, likely for complications such as severe dehydration, pneumonia, or croup. Pneumonia is the most common cause of death from measles in young children.²⁴

• Adult Hospitalization: Adults over 20 also faced significant morbidity, with a 12% hospitalization rate.⁵ Measles in adults is often more severe than in school-aged children, carrying higher risks of liver inflammation and acute encephalitis.

6.2 The Return of Mortality

For the first time since 2015, the U.S. recorded measles deaths.

1. Texas (Two Children): Two unvaccinated children in the West Texas outbreak died. One, an 8-year-old girl, died of "measles pulmonary failure," a direct respiratory complication of the viral infection.²¹

2. New Mexico (One Adult): An unvaccinated adult also died, underscoring that the risk of fatality persists across the lifespan.1These three deaths are a stark reminder that even with advanced U.S. medical care, measles can be fatal. The case-fatality rate in this outbreak (approx. 1.5 per 1,000) aligns with historical norms for developed nations but is unacceptable for a preventable disease.

6.3 The Long Shadow: Subacute Sclerosing Panencephalitis (SSPE)

Perhaps the most terrifying aspect of the 2025 resurgence is the "ticking time bomb" of Subacute Sclerosing Panencephalitis (SSPE). SSPE is a fatal, progressive neurodegenerative disorder caused by a persistent measles infection in the brain. It typically manifests 7 to 10 years after the initial infection, leading to behavioral changes, seizures, coma, and inevitable death.²⁵

• The 1-in-600 Statistic: While older literature cited SSPE risks as 1 in 100,000, modern research has radically revised this figure. For infants infected with measles before their first birthday (before they can be vaccinated), the risk of developing SSPE is approximately 1 in 600.²⁶

• Implications for the 2025 Cohort: Given that 537 children under 5 were infected in 2025, and a significant portion were likely infants (evidenced by the 11 babies exposed in Utah), statistical probability suggests that the U.S. may see cases of SSPE emerging from this cohort in the early 2030s.

• The Los Angeles Tragedy: The reality of this risk was underscored in late 2025 when a child in Los Angeles died of SSPE. This child had contracted measles years prior, serving as a tragic contemporaneous example of the virus's delayed lethality.²⁸

7. The Immunology Landscape: Vaccination and the "Immunization Gap"

The engine driving the 2025 resurgence is the erosion of vaccine coverage. Herd immunity against measles requires a threshold of 95% coverage due to the virus's extreme contagiousness. The U.S. has slipped below this safety line.

7.1 National Coverage Declines

Data for the 2024-2025 school year indicates that national MMR coverage among kindergartners dropped to 92.5%.²⁹ This 2.5% gap below the herd immunity threshold is sufficient for the virus to find and exploit transmission channels.

• State-Level Disparities: The national average hides dangerous local variations. In Idaho, coverage dropped to 78.5%. In contrast, Connecticut maintained 98.2% coverage, demonstrating that policy and public sentiment play huge roles in outcomes.³⁰

• Failure of the Safety Net: 39 states reported MMR coverage below the 95% target, meaning the vast majority of the country is now theoretically vulnerable to sustained outbreaks.³¹

7.2 The Rise of Exemptions

The decline in vaccination is largely driven by an increase in non-medical exemptions (NMEs).

• Record Highs: The percentage of kindergartners with an exemption for one or more vaccines reached an all-time high of 3.6% in 2024-2025.²⁹

• Legislative Landscape: Currently, 47 states allow religious or personal belief exemptions. The 2025 outbreaks occurred precisely in the communities where these exemptions are clustered. For example, in the South Carolina outbreak, 172 of the 185 cases were unvaccinated, reflecting a community where exemption is the norm rather than the exception.¹⁵

7.3 Sociological Drivers: The 7C Model

Researchers applying the 7C model of vaccine readiness (Confidence, Complacency, Constraints, Collective responsibility, risk Calculation, Compliance, and Conspiracy) attribute this decline to a "post-COVID hangover".³

• Confidence: Trust in public health authorities plummeted during the pandemic, and this distrust has been transferred to routine childhood immunizations.

• Complacency: Because measles had been eliminated for 25 years, many parents no longer fear the disease, viewing it as a mild rash rather than a potential killer.

• Conspiracy: Misinformation connecting vaccines to autism or other harms has been amplified in online echo chambers, hardening the stance of previously hesitant communities.⁴

8. The Crisis of Elimination: 2026

8.1 The Definition of Failure

The U.S. maintained measles elimination status from 2000 through 2024. However, "elimination" is a technical status, not a permanent achievement. It is defined as the absence of continuous endemic transmission for 12 months. If a single lineage of the virus circulates for more than a year, the disease is considered re-established.⁵

8.2 The January Deadline

Public health officials have identified the West Texas outbreak strain (Genotype D8, sequence 9171) as the threat to this status. This strain began circulating in January 2025.

• The Clock is Ticking: If this specific genetic lineage is detected in cases occurring in late January 2026, it will confirm 12 months of continuous transmission.²

• High Probability of Loss: Given the ongoing outbreaks in the Southwest and the genetic linkage of cases across state lines, the probability of the U.S. losing its elimination status in early 2026 is considered high by experts.¹²

8.3 Implications of Re-establishment

Losing elimination status would align the U.S. with countries where measles is endemic.

• Public Health Resources: It would necessitate a shift from "outbreak containment" (treating each case as an emergency) to "disease control" (managing a constant burden), draining resources from other health priorities.

• Global Standing: It would follow Canada, which lost its status in late 2025, and signal a hemispheric failure in the Americas.³³

• Economic Impact: The cost of containing measles is astronomical. A study of the West Texas outbreak estimated the public health response cost at over $12 million.³⁴

9. Conclusion

As the United States moves through the first week of January 2026, the nation is in the midst of a public health crisis that was both predicted and preventable. The resurgence of measles in 2025, characterized by over 2,000 cases, three deaths, and widespread outbreaks, is the direct result of fraying herd immunity and rising vaccine hesitancy. The virus, ever an opportunist, has found the cracks in the American shield—in the schools of South Carolina, the border towns of Utah and Arizona, and the plains of West Texas.

The immediate future will be determined by the genetic sequencing of cases in January 2026. If the D8 lineage is found to have survived the winter, the U.S. will lose its elimination crown. However, the true cost is already counted in the 235 hospitalizations, the three lives lost, and the potential future cases of SSPE that will haunt the 2025 cohort for years to come. Reversing this tide requires more than just biological interventions; it demands a restoration of trust in public health and a renewed societal commitment to the collective defense of the most vulnerable.

Works cited

1. Measles Update — United States, January 1–April 17, 2025 | MMWR - CDC, accessed January 3, 2026, https://www.cdc.gov/mmwr/volumes/74/wr/mm7414a1.htm

2. Public Health Wake-Up Call: Will the US Lose Measles Elimination Status? | Contagion Live, accessed January 3, 2026, https://www.contagionlive.com/view/public-health-wake-up-call-will-the-us-lose-measles-elimination-status-

3. Measles containing vaccine hesitancy and readiness in the post-COVID-19 era: A 7C model commentary - PubMed Central, accessed January 3, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC12560032/

4. The 2025 United States Measles Crisis: When Vaccine Hesitancy Meets Reality - PMC - NIH, accessed January 3, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC12357784/

5. Measles Cases and Outbreaks - CDC, accessed January 3, 2026, https://www.cdc.gov/measles/data-research/index.html

6. U.S. Measles Cases Hit Highest Level Since Declared Eliminated in 2000 | International Vaccine Access Center - Johns Hopkins Bloomberg School of Public Health, accessed January 3, 2026, https://publichealth.jhu.edu/ivac/2025/us-measles-cases-hit-highest-level-since-declared-eliminated-in-2000

7. Measles Update — United States, January 1–April 17, 2025 - PMC - NIH, accessed January 3, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC12021071/

8. Epidemiological Update Measles in the Americas Region - PAHO, accessed January 3, 2026, https://www.paho.org/sites/default/files/2025-09/2025-sept-19-phe-measles-epi-update-final-2.pdf

9. The basic reproduction number (R 0 ) of measles: a systematic review - PubMed, accessed January 3, 2026, https://pubmed.ncbi.nlm.nih.gov/28757186/

10. Measles 2025 Outbreak - BV-BRC, accessed January 3, 2026, https://www.bv-brc.org/outbreaks/Measles/

11. Predicting the Airborne Transmission of Measles: Impact of Indoor Carbon Dioxide (CO2) Levels and Mitigation Strategies - NIH, accessed January 3, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC11330571/

12. US likely to lose measles eradication status in 2026, accessed January 3, 2026, https://www.washingtonexaminer.com/policy/healthcare/4379205/us-likely-to-lose-measles-eradication-status-2026/

13. Measles outbreaks could cost US its 25-year elimination status, accessed January 3, 2026, https://www.kpcw.org/summit-county/2025-12-10/measles-outbreaks-could-cost-us-its-25-year-elimination-status

14. Measles Scenario-Based Human Health Risk Assessment for the United States, accessed January 3, 2026, https://publichealth.jhu.edu/sites/default/files/2025-02/Measles-Risk-Assessment-1.31.25.pdf

15. 2025 Measles Outbreak | South Carolina Department of Public Health, accessed January 3, 2026, https://dph.sc.gov/diseases-conditions/infectious-diseases/measles-rubeola/2025-measles-outbreak

16. WHO alert on US measles outbreak adds new genetic details | CIDRAP, accessed January 3, 2026, https://www.cidrap.umn.edu/measles/who-alert-us-measles-outbreak-adds-new-genetic-details

17. Measles - United States of America - World Health Organization (WHO), accessed January 3, 2026, https://www.who.int/emergencies/disease-outbreak-news/item/2025-DON561

18. From multiple measles genotype D8 introductions in 2024 to sustained B3 local transmission in and around Milan, northern Italy, January to April 2025 - PMC - NIH, accessed January 3, 2026, https://pmc.ncbi.nlm.nih.gov/articles/PMC12105090/

19. Measles Outbreak – August 12, 2025 | Texas DSHS, accessed January 3, 2026, https://www.dshs.texas.gov/news-alerts/measles-outbreak-2025

20. Texas measles outbreak hardened Mennonites against vaccines - The Texas Tribune, accessed January 3, 2026, https://www.texastribune.org/2025/12/17/texas-measles-mennonite-seminole-aftermath/

21. 2025 United States measles outbreak - Wikipedia, accessed January 3, 2026, https://en.wikipedia.org/wiki/2025_United_States_measles_outbreak

22. US exceeds 1,900 measles cases as outbreaks expand - CIDRAP, accessed January 3, 2026, https://www.cidrap.umn.edu/measles/us-exceeds-1900-measles-cases-outbreaks-expand

23. CDC confirms 23 more US measles cases as 2025 total tops 1,500 - CIDRAP, accessed January 3, 2026, https://www.cidrap.umn.edu/measles/cdc-confirms-23-more-us-measles-cases-2025-total-tops-1500

24. Measles – NFID, accessed January 3, 2026, https://www.nfid.org/infectious-disease/measles/

25. The looming threat of subacute sclerosing panencephalitis: A call for action, accessed January 3, 2026, https://www.movementdisorders.org/Moving-Along/subacute-sclerosing-panencephalitis

26. Vaccine News & Notes — October 2025 | Children's Hospital of Philadelphia, accessed January 3, 2026, https://www.chop.edu/parents-pack/parents-pack-newsletter/vaccine-news-notes-october-2025

27. Child dies from complications of measles years after infection – SSPE explained, accessed January 3, 2026, https://www.gavi.org/vaccineswork/child-dies-complications-measles-years-after-infection-sspe-explained

28. LA County confirms child's death from late measles complication | CIDRAP, accessed January 3, 2026, https://www.cidrap.umn.edu/measles/la-county-confirms-childs-death-late-measles-complication

29. Vaccination Coverage and Exemptions among Kindergartners | SchoolVaxView - CDC, accessed January 3, 2026, https://www.cdc.gov/schoolvaxview/data/index.html

30. Across the U.S., Childhood Vaccination Rates Continue to Decline, accessed January 3, 2026, https://publichealth.jhu.edu/ivac/2025/across-the-us-childhood-vaccination-rates-continue-to-decline

31. Kindergarten Routine Vaccination Rates Continue to Decline - KFF, accessed January 3, 2026, https://www.kff.org/medicaid/kindergarten-routine-vaccination-rates-continue-to-decline/

32. CDC data finds kindergarten vaccination rates declined during 2024-25 school year | AHA News, accessed January 3, 2026, https://www.aha.org/news/headline/2025-08-04-cdc-data-finds-kindergarten-vaccination-rates-declined-during-2024-25-school-year

33. What CDC is Doing About Global Measles, accessed January 3, 2026, https://www.cdc.gov/global-measles-vaccination/what/index.html

34. Texas outbreak could cause U.S. to no longer be measles-free - The Texas Tribune, accessed January 3, 2026, https://www.texastribune.org/2025/12/05/texas-measles-outbreak-spread-elimination/

35. The Measles Outbreak in West Texas and Beyond | Johns Hopkins, accessed January 3, 2026, https://publichealth.jhu.edu/2025/the-measles-outbreak-in-west-texas-and-beyond

36. CDC social media silence during 2025 measles outbreak left void filled by news media, study suggests | CIDRAP, accessed January 3, 2026, https://www.cidrap.umn.edu/measles/cdc-social-media-silence-during-2025-measles-outbreak-left-void-filled-news-media-study

37. Measles Elimination Status: What It Is and How the U.S. Could Lose It | KFF, accessed January 3, 2026, https://www.kff.org/other-health/measles-elimination-status-what-it-is-and-how-the-u-s-could-lose-it/

38. FastStats - Measles - CDC, accessed January 3, 2026, https://www.cdc.gov/nchs/fastats/measles.htm

39. PAHO calls for regional action as the Americas lose measles elimination status, accessed January 3, 2026, https://www.paho.org/en/news/10-11-2025-paho-calls-regional-action-americas-lose-measles-elimination-status

40. Pediatric Vaccine Hesitancy in the United States—The Growing Problem and Strategies for Management Including Motivational Interviewing - MDPI, accessed January 3, 2026, https://www.mdpi.com/2076-393X/13/2/115

41. Parental Factors Associated With Measles–Mumps–Rubella Vaccination in US Children Younger Than 5 Years | AJPH | Vol. 115 Issue 3, accessed January 3, 2026, https://ajph.aphapublications.org/doi/10.2105/AJPH.2024.307912

42. Modelling measles transmission dynamics and the impact of control strategies on outbreak Management - Taylor & Francis, accessed January 3, 2026, https://www.tandfonline.com/doi/pdf/10.1080/17513758.2025.2479448

43. Modelling measles transmission dynamics and the impact of control strategies on outbreak Management - ResearchGate, accessed January 3, 2026, https://www.researchgate.net/publication/389940455_Modelling_measles_transmission_dynamics_and_the_impact_of_control_strategies_on_outbreak_Management

44. Full article: Modelling measles transmission dynamics and the impact of control strategies on outbreak Management, accessed January 3, 2026, https://www.tandfonline.com/doi/full/10.1080/17513758.2025.2479448?af=R

45. Local experts warn US may lose measles elimination status after 25 years - KSAT, accessed January 3, 2026, https://www.ksat.com/news/local/2025/12/16/local-experts-warn-us-may-lose-measles-elimination-status-after-25-years/

46. Texas announces end of West Texas measles outbreak, accessed January 3, 2026, https://www.dshs.texas.gov/news-alerts/texas-announces-end-west-texas-measles-outbreak

47. How Regions Earn and Keep Their "Measles-Free" Status | History of Vaccines, accessed January 3, 2026, https://historyofvaccines.org/blog/how-regions-earn-and-keep-their-measles-free-status/

48. Utah and South Carolina Measles Outbreaks Share Similar Vaccination Status, accessed January 3, 2026, https://www.vax-before-travel.com/2026/01/02/utah-and-south-carolina-measles-outbreaks-share-similar-vaccination-status

49. MEASLES OUTBREAK - SOUTHWEST U.S. - 2025 - Campus Health, accessed January 3, 2026, https://campushealth.yale.edu/sites/default/files/2025-07/YSPH%20VMOC%20Special%20Report%20-%20Measles%20Outbreak%20%20Southwest%20US%207-6-2025.pdf