Worst US measles outbreak since 2000

Summary

Beginning in January 2025, a measles outbreak centered in Texas and New Mexico spread to 25+ states, producing 2,289 confirmed 2025 cases - the highest annual total since the US declared elimination in 2000. Three people died in the 2025 outbreak, and Los Angeles County reported a child's death from a late complication of a measles infection acquired in infancy. The outbreak continued into 2026 with 3,659 additional confirmed cases as of September 24, 2026, per CDC.

What happened

The 2025 southwest outbreak originated in an unvaccinated community in west Texas, rapidly spreading to New Mexico and Oklahoma. By April 17, 2025, 800 cases had been confirmed (MMWR); full-year 2025 cases reached 2,289 across 48 outbreaks. Three deaths occurred in 2025: two unvaccinated school-aged children in Texas and one unvaccinated adult in New Mexico - the first US measles deaths in approximately ten years. In September 2025, Los Angeles County reported the death of a school-aged child from subacute sclerosing panencephalitis (SSPE), a complication of a measles infection acquired in infancy. In 2026, Pennsylvania reported four measles-associated deaths; CDC's national tracker listed two 2026 deaths as of September 25. In 2026, a further 3,659 confirmed cases had been recorded as of September 24 across 40 new outbreaks, per CDC. The US is now at risk of losing its official measles-elimination status, with a regional review of the country's measles-elimination status postponed from April to November 2026. Vaccination rates had been sliding for years before 2025 - kindergarten MMR coverage was 92.5% in 2024-25, down from 95.2% pre-pandemic - and public-health experts warn that federal vaccine-skeptic messaging and the removal of COVID-19 vaccine recommendations from the childhood schedule (later reversed by court) risk deepening that decline.

Impact on the United States

Measles deaths: three in the 2025 outbreak (two unvaccinated children in Texas, one unvaccinated adult in New Mexico); a Los Angeles County child who died in 2025 of SSPE from a measles infection acquired years earlier as an infant; and four measles-associated deaths reported by Pennsylvania in 2026 (CDC's tracker listed two 2026 deaths as of September 25). More than 5,900 cases across 2025-2026; potential loss of WHO measles-elimination status conferred in 2000; about 280,000 kindergartners without documentation of completing the MMR series (2025-26 school year).

Documented effects

1. 2,289 US measles cases in full-year 2025; highest since elimination declared in 2000; 3 deaths in the 2025 southwest outbreak[1][2]
2. 3,659 confirmed cases in 2026 as of September 24, 2026, from 40 new outbreaks; more than 5,900 cases across 2025-2026[2]
3. Kindergarten MMR coverage 92.5% in 2024-25 and 92.4% in 2025-26, below the 95% threshold; about 280,000 kindergartners lacked documentation of completing the MMR series in 2025-26[3][7]
4. Sep 2026Pennsylvania reported four measles-associated deaths in 2026 (August-September), all unvaccinated; CDC's national tracker listed one 2026 death as of September 24 while a standard death definition is developed, and two in its September 25 update[4][5][2]
5. Mar 2, 2026PAHO moved its review of US measles elimination status to its regular meeting in November 2026, citing ongoing US analysis including complete viral genome sequencing[8]

Why this is rated critical

The first US measles deaths in about a decade, more than 5,900 cases across 2025-2026, and a pending review of US measles-elimination status - a serious and partly irreversible public-health harm.

Corrections & updates [10]

Every change to a fact on this page after publication is logged here, newest first.

1. Sep 29, 2026UpdatedFigures

   Case counts updated. CDC now reports 2,289 confirmed cases for full-year 2025 (previously listed as 2,288) and 3,659 confirmed cases in 2026 as of September 24, 2026 (previously 2,104 as of June 18), from 40 new outbreaks. The combined 2025-2026 total is now more than 5,900.[2]

2. Sep 29, 2026UpdatedDeaths

   Pennsylvania has reported four measles-associated deaths in 2026 (two infants in Lancaster County in August, and two in September in Jefferson and Mifflin counties), all unvaccinated. As of late September 2026, CDC counted one 2026 measles death on its national tracker while it works with state epidemiologists on a standard definition for measles-associated deaths.[4][5]

3. Sep 29, 2026UpdatedElimination review

   The regional review of US measles-elimination status, first set for April 2026, was postponed to November 2026 to coincide with the annual meeting of PAHO's regional verification commission (KFF).[6]

   + Show previous and current text- Hide previous and current text

   Previously

   The 2025 southwest outbreak originated in an unvaccinated community in west Texas, rapidly spreading to New Mexico and Oklahoma. By April 17, 2025, 800 cases had been confirmed (MMWR); full-year 2025 cases reached 2,288 across 48 outbreaks. Three deaths occurred in 2025: two unvaccinated school-aged children in Texas and one unvaccinated adult in New Mexico - the first US measles deaths in approximately ten years. A fourth death (a child, Los Angeles County) was later confirmed. In 2026, a further 3,659 confirmed cases had been recorded as of September 24 across 40 new outbreaks, per CDC. The US is now at risk of losing its official measles-elimination status, with a review of the country's measles-elimination status pending (its timing reportedly delayed). Vaccination rates had been sliding for years before 2025 - kindergarten MMR coverage was 92.5% in 2024-25, down from 95.2% pre-pandemic - and public-health experts warn that federal vaccine-skeptic messaging and the removal of COVID-19 vaccine recommendations from the childhood schedule (later reversed by court) risk deepening that decline.

   Now

   The 2025 southwest outbreak originated in an unvaccinated community in west Texas, rapidly spreading to New Mexico and Oklahoma. By April 17, 2025, 800 cases had been confirmed (MMWR); full-year 2025 cases reached 2,288 across 48 outbreaks. Three deaths occurred in 2025: two unvaccinated school-aged children in Texas and one unvaccinated adult in New Mexico - the first US measles deaths in approximately ten years. A fourth death (a child, Los Angeles County) was later confirmed. In 2026, a further 3,659 confirmed cases had been recorded as of September 24 across 40 new outbreaks, per CDC. The US is now at risk of losing its official measles-elimination status, with a regional review of the country's measles-elimination status postponed from April to November 2026. Vaccination rates had been sliding for years before 2025 - kindergarten MMR coverage was 92.5% in 2024-25, down from 95.2% pre-pandemic - and public-health experts warn that federal vaccine-skeptic messaging and the removal of COVID-19 vaccine recommendations from the childhood schedule (later reversed by court) risk deepening that decline.

4. Sep 29, 2026CorrectedKey facts / Source

   The kindergarten-vaccination figures were attributed to a CDC measles update that does not contain them, and the "286,000 unprotected kindergartners" figure could not be found in any cited source. The 92.5% coverage figure (2024-25) is confirmed by PBS and KFF. CDC's latest SchoolVaxView data (2025-26 school year, published August 2026) put MMR coverage at 92.4% and about 280,000 kindergartners without documentation of completing the MMR series; the entry now uses that figure.[3][7]

5. Sep 29, 2026UpdatedKey facts

   Updated: in its September 25, 2026 update CDC's national tracker listed two measles deaths in 2026, up from one.[2]

6. Sep 29, 2026UpdatedKey facts

   Added the source for the postponed review: on March 2, 2026 PAHO said it would review US measles elimination status at its regular meeting in November 2026, citing ongoing US analysis including complete viral genome sequencing.[8]

7. Sep 29, 2026CorrectedDeaths and case count

   The entry counted '4 deaths' as if all came from the outbreak, and gave 2,288 as the 2025 case total. Three people died in the 2025 Texas/New Mexico outbreak. The fourth death, which previously had no source, was a school-aged Los Angeles County child who died of subacute sclerosing panencephalitis (SSPE), a complication of a measles infection acquired in infancy, as the county health department announced on September 11, 2025. Separately, Pennsylvania has reported four measles-associated deaths in 2026, while CDC's national tracker listed two 2026 deaths as of September 25. CDC's full-year 2025 total is 2,289 confirmed cases.[9][2][4][5]

8. Sep 29, 2026ClarifiedSeverity rationale

   The severity rationale characterized the outbreak as a 'public-health failure'; it now states the documented deaths, cases and elimination-status review. Severity unchanged.

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   Previously

   First US measles deaths in a decade with 5,900+ cases and elimination status at risk, a systemic and partly irreversible public-health failure.

   Now

   The first US measles deaths in about a decade, more than 5,900 cases across 2025-2026, and a pending review of US measles-elimination status - a serious and partly irreversible public-health harm.

9. Sep 29, 2026CorrectedDisplay copy

   The summary said vaccine-skeptic messaging 'contributed to the scale' of the outbreak; the record says only that vaccination rates had been sliding for years and that experts warn federal messaging risks deepening the decline. The summary now matches the record.[3]

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   Previously

   A west Texas outbreak spread to dozens of states in 2025, producing the most cases since elimination and the first US measles deaths in a decade. Declining vaccination rates and vaccine-skeptic messaging contributed to the scale.

   Now

   A west Texas outbreak spread to dozens of states in 2025, producing the most cases since elimination and the first US measles deaths in a decade. Kindergarten vaccination rates had been sliding for years, and public-health experts warn that federal vaccine-skeptic messaging risks deepening that decline.

10. Sep 29, 2026CorrectedCost estimate

    The booked cost now uses a published Johns Hopkins cost model (a fixed cost per outbreak plus about $16,197 per case) and CDC's current case count, replacing a per-case figure from a source that could not be opened and an unsourced Medicaid add-on. An unsourced federal run-rate is removed from the 10- and 15-year figures. The broader cost is rebuilt from Yale's verifiable $1.5B-a-year projection, replacing an unverifiable $7.8B total.

    Previously

    net $200M so far; 10yr $1.5B; 15yr $2.5B; broader $7.8B

    Now

    net $106M so far; 10yr $106M; 15yr $106M; broader $4.5B

Sources [9]