Measles Update: September 18, 2026

With schools back in session, the beginning of the respiratory virus season, and measles cases seeing an uptick, we will be starting up our weekly measles tracker to provide an update on the number of cases being reported in the US.

Today, the Centers for Disease Control and Prevention (CDC) reported there were 3,471* cases of measles in the US as of September 17, 2026. Week-over week, that is an additional 177 cases and a 5.37% increase. Last week, the federal agency reported there was 3,294* confirmed cases.¹ This continues a trend of a surge seen in the number of cases from the previous week.

CDC said there were 3,454 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 39 new outbreaks** reported in 2026, and 95% of confirmed cases (3,296 of 3,471) are outbreak-associated (1,920 from outbreaks in 2026 and 1,376 from outbreaks that started in 2025).” ¹

Pennsylvania’s Deadly Outbreak

Pennsylvania is in the throes of its worst measles outbreak in decades. The fourth measles-related death was just reported in the state earlier this week. For this latest death, the Mifflin County coroner announced an 18-year-old resident had died “due to complications of measles,” which was identified as acute disseminated encephalomyelitis (ADEM).²

No other information about the teen was shared by the coroner or the state health department. Just a few days before that, the Jefferson County, PA, coroner announced a measles death of a 40-year old woman who was unvaccinated.

As of September 16, the state’s Department of Health was reporting 731 cases in 38 of the 67 counties. In late August, the state had reported 393 cases in 28 counties, indicating an over 300-case increase in just a few weeks. And the state has one of the largest numbers of cases in the country.³

Within the last few weeks, Pennsylvania health officials also reported 2 measles-related deaths in babies. One was a newborn who died shortly after birth, and the other was a 6-week-old infant.

New Federal Reporting of Measles Deaths Marks Major Change

When you look at the current CDC measles tracker, viewers will not see any measles deaths for this year. The agency decided to make a change and will now gather data from the National Center for Health Statistics when it reports measles death counts.⁴ This system is not meant to confirm individual cases; therefore it is likely no deaths will be reported in the future.

With the fourth measles-related death in 2026, this surpasses the total for all of 2025, which had 3 deaths.

2026 Breaks 35-year Record

Back at the end of July, The US confirmed more measles cases in 2026 than in any year since 1991, with 5 months still remaining on the calendar.⁵ The Johns Hopkins University measles tracker counted 2295 cases as of July 22, edging past the 2289 cases reported for the full year of 2025 and marking the highest annual total since measles was declared eliminated in the country in 2000.⁶

Whereas, the CDC measles tracker pulls state counts, the Hopkins tracker pulls data more directly and rapidly from participating state/territorial health departments, plus county health departments and even news releases or news articles, giving faster, more granular updates.

*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 measles library of articles and clinician commentary.

References

1.Measles Cases and Outbreaks. CDC. April 17, 2026. Accessed April 17, 2026.
https://www.cdc.gov/measles/data-research/index.html

2.Bendix A, Edwards E. Pennsylvania teen dies from measles complications, health officials report. NBC News. September 15, 2026. Accessed September 16, 2026.
https://www.nbcnews.com/health/health-news/pennsylvania-teen-dies-measles-complications-coroner-cdc-2026-rcna597980

3.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

4. CDC Lists No Measles Deaths For 2026 After It Changes Its Tracking Method. KFF Health News. September 15, 2026. Accessed September 18, 2026.
https://kffhealthnews.org/morning-breakout/administration-news-091526/

5. Measles cases and outbreaks. CDC. Updated July 16, 2026. Accessed July 23, 2026. https://www.cdc.gov/measles/data-research/index.html

6. Vision Monday Staff. Measles cases set 35-year US record with months to go in 2026. VisionMonday. Published July 22, 2026. Accessed July 23, 2026. https://www.visionmonday.com/eyecare/health-watch/article/measles-cases-set-35year-us-record-with-months-to-go-in-2026