Pennsylvania tops 900 measles cases, as its largest outbreak in 30 years spreads
Chester County is the only Philadelphia region county where the virus is actively spreading.
Measles cases in Pennsylvania topped 900 this week, as the state’s largest outbreak in three decades continues to spread from rural Lancaster County communities into Philadelphia’s suburbs.
The Pennsylvania Department of Health reported 114 new cases in the last week, reaching a total of 903 cases this year as of Monday. That includes 83 cases in Chester County, the only county in the Philadelphia region where the virus is actively spreading in an outbreak that is also the nation’s largest currently.
Chester County’s outbreak has emerged as the third largest in the state, having more than tripled in size since early August.
Physicians and local health officials say the current case count is likely an undercount, with many cases going unreported.
Cases in Chester County have largely been concentrated along its western border with Lancaster County. But health experts expect the virus to continue to spread statewide. More than half of Pennsylvania’s counties already are affected, as vaccination rates have declined in many communities.
Overall, Chester County has a 94.5% measles vaccination rate among kindergarten students, just below the 95% of people scientists say need to be vaccinated to prevent the virus from spreading within a community.
The so-called herd immunity threshold for measles is high because the virus is so contagious: Nine out of 10 unvaccinated people who come into contact with measles will get sick.
In response to the outbreak, the county’s health department has ramped up communications and outreach, sent nurses into schools and close-knit communities, and held pop-up clinics. The overarching goal of all these efforts: Get more people vaccinated.
Two doses of the measles vaccine offer 97% protection against the virus.
“We are working all the time with organizations, businesses, community leaders — whoever we can get the attention of in the communities impacted,” Jeanne Franklin, the county’s health director, said in an interview last week.
The county has administered 538 measles, mumps, and rubella (MMR) vaccines this year, most of them since the outbreak began in April, she said.
Measles spreading in Pennsylvania
Across Pennsylvania, at least one measles case has been reported in 39 of 67 counties.
Almost all have been among unvaccinated individuals. The state reported four rare “breakthrough” cases of measles in vaccinated people earlier this month.
The virus’ most common symptoms include a fever, cough, runny nose, watery eyes, and a telltale splotchy red rash.
Most people recover, but rare complications can be deadly.
Pennsylvania has reported four measles-associated deaths, all affecting people who were unvaccinated and confirmed to have measles infections.
The deceased include two infants from Amish families in Lancaster County, an 18-year-old in Mifflin County who died from a serious neurological complication of measles, and a 40-year-old woman in Jefferson County with severe respiratory conditions.
As of Monday, Lancaster County had the largest outbreak, with 363 cases. There have been 106 cases in Mifflin County.
