The latest CDC numbers show a 5.37% increase of measles cases from week-to-week. In Pennsylvania, the fourth measles-related death was reported in 2026. Additionally, the CDC has made a change in the way it will report deaths.
News|Articles|September 25, 2026
Measles Update: September 25, 2026
Author(s)John Parkinson
The latest CDC numbers show a 5.4% increase of measles cases from week-to-week. This year has already become the worst for the number of measles cases in the US since the disease was declared eliminated in 2000. With the start of respiratory virus season, case numbers are expected to continue to increase significantly.
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Today, the Centers for Disease Control and Prevention (CDC) reported there were 3,659* cases of measles in the US as of September 24, 2026. Week-over-week, this is an additional 188 cases and a 5.4% increase. Last week, the federal agency reported there were 3,471* confirmed cases.1
CDC said there were 3,642 measles cases were reported by 47 jurisdictions: Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York City, New York State, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming. A total of 17 measles cases were reported among international visitors to the United States.1
The federal agency reports there have been 40 new outbreaks** reported in 2026, and 95% of confirmed cases (3,478 of 3,659) are outbreak-associated (2,094 from outbreaks in 2026 and 1,384 from outbreaks originating in 2025).1
Pennsylvania’s Numbers Continue to Climb
Pennsylvania continues to be one of the states with the largest number of new cases. As of September 23, the state’s Department of Health was reporting 835 cases in 39 of the 67 counties.2 This means there were 104 new cases reported week over week, and a 14.2% increase during that period. The state says there has been 164 hospitalizations and 4 measles-associated deaths.2
A news report covered the disease burden largely in the Amish community in Lancaster County, Pennsylvania with a population largely unvaccinated and vulnerable to measles. In another part of the state, one infectious disease physician at a medical center in Danville said he has seen well over 90 cases of measles this year.3
In response to the outbreak, health officials have administered nearly 5,200 MMR vaccinations at 156 pop-up vaccination clinics in the affected communities since the outbreak began in late April. Dozens of additional vaccine clinics are scheduled for the upcoming weeks and months, based on community interest and need. Overall, state health center staff have administered more than 7,700 MMR vaccine doses to residents in 2026.2
MMR Vaccination Rates Across the US
In looking at the above CDC figure of the US MMR vaccination rates for 2025-2026 across the states, Pennsylvania, South Carolina, Utah, and Texas, which have all seen outbreaks going back to 2025, are all below the herd immunity threshold of 95%. Without that threshold of at least 95% of people vaccinated, local communities are vulnerable to outbreaks.1
In fact, only 10 states exceed the 95% vaccination rate, which could lead to further measles outbreaks in those areas, especially as the US is entering into respiratory virus season. MMR vaccination coverage among kindergartners has fallen from 95.2% in the 2019-2020 school year to 92.4% in 2025-2026, according to CDC.1
2026 Case Count Surpasses Any Year Since Elimination
With three months remaining in 2026, the national case count has already exceeded every full year on record since measles elimination was declared in the United States in 2000. The previous high point in the elimination era came in 2019, when CDC reported 1,274 confirmed cases for the full year.1 The 2025 full-year total, 2,289 cases, also fell short of this year's running tally.1
*It is important to note that the CDC says on its website that the federal agency is aware of probable measles cases being reported by jurisdictions. However, the data on this page only include confirmed cases that jurisdictions notified the CDC about. Therefore, there could be higher numbers in the US overall.
**CDC reports the cumulative number of measles outbreaks (defined as 3 or more related cases) that have occurred this year in the US; states have the most up-to-date information about cases and outbreaks in their jurisdictions.
Continue to check back with Contagion for our weekly updates, news announcements around the disease, and clinician commentary. In addition, we have a
References
1.Measles Cases and Outbreaks. CDC. September 25, 2026. Accessed September 25, 2026.
https://www.cdc.gov/measles/data-research/index.html
2. Measles. Pennsylvania Department of Health. September 16, 2026. Accessed September 18, 2026. https://www.pa.gov/agencies/health/newsroom/pa-department-of-health-provides-statewide-update-on-measles-out3
3.Helmen P. Measles is spreading through Pennsylvania’s Amish country. Doctors are scrambling to keep up. MS Now. September 25, 2026. Accessed September 25, 2026.
https://www.ms.now/news/measles-pennsylvania-amish-outbreak
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