The Centers for Disease Control and Prevention added 101 confirmed measles cases to its national count this week, and two neighboring states supplied most of them. Pennsylvania reported 61 of the new infections, and Ohio reported 24, together accounting for roughly 84 percent of the weekly increase.
That concentration is what is new. The national total now stands at 2,566 for 2026, current through August 13, and this is the second consecutive week of about 100 new cases after several weeks running at roughly half that pace, according to the CDC's measles tracker and an analysis by the Center for Infectious Disease Research and Policy.
For households in central Pennsylvania and northeast Ohio, the timing collides with a decision already sitting on the kitchen table. School districts across both states will open within days.
Lancaster County Now Holds Half of Pennsylvania's Cases
Pennsylvania has recorded 296 cases in 2026, and at least 145 of them, roughly 49 percent, are in Lancaster County, according to the Pennsylvania Department of Health. Neighboring York, Chester, and Lebanon counties have each reported at least a dozen cases, and cases have also appeared in Lehigh and Bedford counties. More than 30 people statewide have been hospitalized.
The state reports that none of the patients diagnosed this year were fully vaccinated. Lancaster County has no independent health department, and local officials have publicly discussed creating one, which shapes how quickly community-level messaging reaches households there.
Dr. Jeffrey Martin, chair of the department of family and community medicine at Penn Medicine's Lancaster General Health, told WITF the surge is unlike anything he has seen in 30 years. "It's a little bit surreal right now," he said. Many of the patients in the hospital have been adults, he noted, even though measles is most common in children. "I'm definitely worried about the school season," Martin said. "That we are going to see more pediatric and children's cases of measles."
An Ohio Cluster That Traces Back Across the Pennsylvania Line
Ohio has confirmed 69 cases this year, an increase of 24 in a single week, according to state infectious disease data. Geauga County has moved from two cases at the end of July to 16 this week, and Harrison County reported its first case, bringing the number of affected Ohio counties to 11.
The link between the two states is not abstract. Health officials have said that earlier Ohio cases in Ashtabula and Tuscarawas counties involve people who may have been exposed at a horse sale auction in North Bloomfield, at the Sugarcreek stockyard, or at an auction in Lancaster County, Pennsylvania, at events held in early to mid July. Large community gatherings that draw attendance across state lines are moving the virus along a corridor rather than within a single county.
Ohio Department of Health Director Dr. Bruce Vanderhoff was blunt about what follows. "All of these cases involve those who are unvaccinated or undervaccinated. Given the exposures of large community events, we unfortunately expect this case count to grow," he said in comments reported by Fox 8. Vanderhoff also cited a slide in the share of Ohio kindergarteners meeting all vaccine requirements, from 89.9 percent to 85.4 percent over six years.
The Numbers That Describe Who Is Actually Getting Sick
Nationally, 19 percent of 2026 cases are in children five and under, and 67 percent are in children and teenagers. Seven percent of patients have been hospitalized, down from 11 percent in 2025. Among all patients, 93 percent were unvaccinated or had unknown vaccination status. No measles deaths have been reported this year, following three deaths last year.
Two doses of the measles, mumps, and rubella vaccine are about 97 percent effective, and one dose is about 93 percent effective. Communities generally need roughly 95 percent coverage to interrupt transmission, which is why one district can absorb an introduction while a neighboring district cannot. National kindergarten coverage has slipped in recent years, and district-level variation matters more than the state average when a case arrives.
Parents should also know that the executive order signed this month, which urges childhood vaccines to be given at separate visits and calls for splitting the combined MMR shot, does not change what is available at a pediatric office or pharmacy today. Separate measles, mumps, and rubella vaccines are not licensed in the United States, and producing them would require both manufacturer participation and FDA approval. The combined vaccine remains the product in supply.
MedicalDaily previously reported that a federal panel is reviewing the country's measles elimination status.
Practical Steps Before the First Day of Class
Check immunization records now rather than at the school door. Children are routinely due for a first MMR dose at 12 to 15 months and a second at four to six years, and a second dose can be given earlier than four if a provider recommends it during an outbreak. Adults uncertain of their status can ask a clinician about records or antibody testing.
Anyone who develops a fever with cough, runny nose, and red watery eyes, followed by a rash, should call a provider or the emergency department before arriving so the visit can be arranged without exposing others. Measles can cause pneumonia, brain swelling, and hospitalization, and infants under one, pregnant people, and immunocompromised residents carry the highest risk.
MMR vaccination is covered without cost sharing by most insurance plans, and the federal Vaccines for Children program covers uninsured and underinsured children at participating providers. Both state health departments have promoted vaccination through local clinics and pharmacies. The CDC updates its national count weekly, and both states update their dashboards during the week.
Key Questions Answered
How many cases were added this week? The CDC confirmed 101 new cases, bringing the 2026 national total to 2,566 as of August 13.
Why are Pennsylvania and Ohio the focus? They accounted for 85 of the 101 new cases. Pennsylvania added 61, and Ohio added 24, the largest state-level increases in the country this week.
Which counties are hardest hit? Lancaster County holds at least 145 of Pennsylvania's 296 cases. In Ohio, Geauga County has grown from two cases in late July to 16.
How is the virus moving between the two states? Officials have linked several Ohio cases to livestock auctions and similar community events, including one held in Lancaster County, Pennsylvania.
Does my child need an extra dose before school? Not automatically. The routine schedule is two doses, but families in outbreak counties should ask a pediatrician whether earlier timing of the second dose is appropriate.
What should I do if my child develops a rash? Call the provider or emergency department before going in, describe the symptoms and any possible exposure, and follow their instructions on how to enter the building.
Where can families get vaccinated at low cost? Most insurance covers MMR with no cost sharing, and the Vaccines for Children program covers eligible uninsured and underinsured children at participating clinics.
