Measles Tracker: April 27 Update

Apr 28, 2025

Top States Reporting New Cases

Most affected age group: Children and adolescents aged 5–19 years, accounting for 338 cases (38% of all cases).
Highest hospitalization risk: Children under 5 years old, with 20% hospitalized (53 out of 266 cases). Younger children are at higher risk for severe complications, including pneumonia, encephalitis (brain swelling), and death.
Vaccination status: 97% of reported cases were either unvaccinated or had an unknown vaccination status — highlighting persistent gaps in immunization coverage.

Measles cases are rising sharply across the U.S., with children and teens (under 20) making up nearly 68% of all cases.
Children under 5 face the greatest risk of hospitalization and severe outcomes.
Vaccination remains critical: The overwhelming majority (97%) of measles cases are among those who are unvaccinated or whose vaccination status is unknown.
Regional outbreaks, especially in West Texas, are fueling broader interstate spread.

Get vaccinated with the MMR (measles, mumps, rubella) vaccine. Two doses are about 97% effective at preventing measles.
Ensure children receive all recommended doses on schedule:
- First dose: 12–15 months of age
- Second dose: 4–6 years of age
Infants (6–11 months) traveling internationally or to outbreak areas should receive an early MMR dose.
Stay home and isolate if you develop measles symptoms: fever, rash, cough, runny nose, or red eyes.
Notify your healthcare provider immediately if you suspect measles—before arriving at a clinic or hospital.
- Wear a well-fitting mask (N95, KN95, or surgical) if you must visit a healthcare facility to minimize the risk of spreading the virus.
Follow public health guidance during outbreaks, including quarantine recommendations for exposed, unvaccinated individuals.
Encourage vaccination among friends, family, and community members. Herd immunity protects those who cannot be vaccinated (e.g., infants, immunocompromised individuals).

US may have millions more measles cases over next 25 years if childhood vaccination rates continue to decline, study says: If routine childhood vaccination rates keep dropping, measles could become endemic in the United States, potentially leading to up to 51 million cases over the next 25 years, according to a new study.
Measles may be making a comeback in the U.S., Stanford Medicine-led research finds: A Stanford-led study warns that measles could become endemic in the U.S. within 20 years if childhood vaccination rates continue to decline.