Philadelphia Reports Chickenpox Outbreaks at 2 Schools

Philadelphia health officials are reporting a “small but notable” uptick in chickenpox cases linked to outbreaks at two city schools. According to The Philadelphia Inquirer, each outbreak involved fewer than 10 cases, and there is no connection between the two.

The city has issued a health advisory to doctors, emphasizing testing, reporting, and awareness of varicella, particularly in unvaccinated children who may experience more severe disease than vaccinated children.

Gayle Mendoza, a spokesperson for the city Department of Public Health, told the Inquirer she did not have any details about how many cases were reported in vaccinated versus unvaccinated children. It's also unclear which factors have contributed to the rise in chickenpox cases.

Mendoza confirmed that public health officials are coordinating with schools affected by the outbreaks to provide response and containment efforts.

Unvaccinated individuals with chickenpox can develop 250 to 500 lesions. Vaccinated individuals who become ill typically have fewer than 50 lesions and are less likely to spread the disease, according to the Inquirer.

Philadelphia maintains high overall vaccination coverage, with approximately 94% of schoolchildren immune to varicella (commonly called chickenpox), primarily through vaccination. Among those with immunity today, only about 1% acquired it through infection, the Inquirer noted.

Philadelphia's varicella vaccination rate briefly dipped after the 2020-2021 school year but rebounded to near pre-pandemic levels by 2024-2025, per state data.

“With the recent outbreaks, Philadelphia health officials are encouraging health providers to test patients for chickenpox and report suspected, probable, and confirmed cases to local authorities,” said Aubrey Whelan of The Philadelphia Inquirer. “People who have been exposed to the virus can get immunized within five days or receive antiviral medications to prevent them from contracting the disease.”