Oxford Area High School in Chester County, Pennsylvania, closed on Friday, October 9, after a confirmed case of measles was identified in the school community, the Oxford Area School District told families in a letter on Thursday, WPVI reported.
"We understand that news like this may be concerning for families," the district wrote. "The health and well-being of our students, staff and community are incredibly important to us, and we recognize that receiving this information can raise questions, concerns and uncertainty."
The Chester County Health Department will contact anyone believed to have been exposed, school officials said. Under the district's letter, anyone who is not vaccinated against measles, or cannot provide proof of vaccination, must stay away from school and school-related activities for 21 days after a possible exposure. The county applies that 21-day rule whenever a school identifies a measles case, The Philadelphia Inquirer reported.
The high school enrolled 1,089 students in grades 9 through 12 in the 2024-25 school year, according to federal data. It is the largest of the district's six schools, which together enrolled 3,129 students.
The closure comes as Pennsylvania deals with its largest measles outbreak in decades. The state Department of Health reported 1,004 cases this year as of October 5, including 198 hospitalizations and five deaths, across 39 counties, NBC10 reported. Pennsylvania has more measles cases than any other state, according to CDC data cited by NBC10.
Chester County has reported 86 cases, according to WPVI. That makes it the third-hardest-hit county in the state, behind Lancaster and Mifflin counties. Most of Chester County's cases have been along its western border with Lancaster County, where the outbreak began, the Inquirer reported. Jeanne Franklin, the county's health director, told the paper that the department began reaching out to hospitals and schools months before the first case arrived.
"If it finds that pocket of unvaccinated individuals, it's going to popcorn until it finds no one left," Franklin said. The county's kindergarten measles vaccination rate is just under 95%, the level scientists consider necessary to keep the virus from spreading widely, the Inquirer reported. Chester County health officials believe the true number of cases is higher than reported, because many people don't seek care unless symptoms are severe, NBC10 reported.
Measles usually starts with a high fever, cough, runny nose, and red, watery eyes, according to the Centers for Disease Control and Prevention. Symptoms begin about 7 to 14 days after exposure. Tiny white spots, called Koplik spots, may appear inside the mouth two to three days after symptoms start. A rash follows three to five days in, beginning on the face at the hairline and spreading down to the neck, trunk, arms, legs, and feet. The fever may spike above 104 degrees when the rash appears.
The CDC recommends two doses of the MMR vaccine, the first at 12 to 15 months old and the second at 4 to 6 years old. One dose is 93% effective against measles, and two doses are 97% effective, the agency says. Our guide on what parents should know about measles and schools covers how school exclusion rules work.
Sources
WPVI 6abc: Oxford Area High School closed Friday after confirmed case of measles
The Philadelphia Inquirer: Chester County has more measles cases than most entire states in the country
NBC10 Philadelphia: Measles cases rise above 1,000 in Pennsylvania, officials say
CDC: Measles Symptoms and Complications
CDC: Measles Vaccine
School and enrollment figures from allk12's analysis of National Center for Education Statistics (NCES) Common Core of Data, 2024-25.
