The acceleration marks the sharpest single-week jump in recent months and pushes the national total well beyond the 2,289 cases recorded for all of 2025, which had already been the highest annual count since 1991. Health officials say the majority of new infections are concentrated in Pennsylvania and Ohio, two states where transmission has intensified across multiple counties.
Pennsylvania and Ohio Drive the Surge
Pennsylvania remains the country’s most active measles hot spot, contributing 89 of the 211 new cases. The state’s year-to-date total now stands at 379, with Lancaster County bearing the brunt at 181 confirmed infections — roughly 48% of the state’s caseload. Chester County follows with 41 cases, while Mifflin and Lebanon counties have logged 25 and 21 respectively.
The outbreak has also reached Allegheny County for the first time since 2019. According to CBS News, a University of Pittsburgh Medical Center spokesperson confirmed that an unvaccinated patient was evaluated at UPMC Children’s Hospital emergency department on August 12 and again on August 18. The Allegheny County Health Department said the patient, who is from outside the county, is now in isolation.
“The Health Department recommends that any person who is due for measles vaccination make arrangements to receive it from their medical provider,” officials said in a news release.
Neighboring Ohio reported 73 new infections, bringing its 2026 total to 142. Ashtabula County leads the state with 40 cases. The outbreak has now spread to 15 Ohio counties, an increase of four from the previous week, signaling widening geographic transmission rather than a contained cluster.
National Picture and Vaccination Gaps
The CDC has logged 36 outbreaks — defined as three or more related cases — though that figure may reflect a reporting anomaly, as the agency had counted 38 the week prior. For context, 2025 saw 48 outbreaks over the full year. Cases have now been confirmed in 45 states plus New York City and Washington, DC.
All but 16 of this year’s cases were locally acquired, with the remainder linked to international travel. The data underscore that sustained domestic transmission, not imported infections, is fueling the outbreak’s expansion.
Vaccination status remains the clearest risk factor. Among all measles patients this year, 94% are unvaccinated or have an unknown vaccine status. Children age 5 and under account for 19% of cases, while kids and teens make up 66% — meaning the vast majority of infections are hitting minors. Seven percent of patients have been hospitalized, down from 11% in 2025, though no measles deaths have been reported this year. Three people, including two children, died of measles in 2025.
Western States Hold Steady
Not every state is seeing rising numbers. Utah, which has the largest active measles outbreak in the country, reported no new cases this week, holding at 518 for the year. The CDC’s measles map lists 526 cases for Utah, a minor discrepancy that typically reflects reporting lags between state and federal systems. Utah recorded 197 cases in 2025.
Washington state held at 55 total cases, Arizona remained at 122, and Virginia stayed at 177. The stability in these states suggests that targeted public health responses may be containing transmission, even as the national trajectory trends upward.
What Happens Next
The doubling of weekly case additions signals that the measles outbreak is entering a more aggressive phase, particularly in Pennsylvania and Ohio. With schools resuming across much of the country, health officials are bracing for potential further spread among unvaccinated children in classroom settings. Lancaster County’s concentration of cases — nearly half of Pennsylvania’s total — will likely remain the focal point for containment efforts.
The Allegheny County case, involving an unvaccinated patient treated at a children’s hospital, illustrates how the outbreak can seed new transmission chains in previously unaffected areas. Public health departments in counties without confirmed cases are urging residents to verify their MMR vaccination status, particularly ahead of the school year. With 94% of cases occurring in unvaccinated or unknown-status individuals, improving vaccine uptake remains the single most effective lever for slowing the outbreak’s momentum.
— Aisha Mensah, health desk, AXO News