Pennsylvania has reported 1,317 confirmed measles cases in 2026, as the outbreak continues to spread across the US state, according to the Pennsylvania Department of Health. The latest update, issued on Wednesday, October 21, recorded 31 additional cases since the department’s previous update on Monday.

The outbreak has now affected 43 counties, with Washington County newly added to the list. Measles-related hospitalisations have increased to 251, up from 247 in the previous update. The state has reported five measles-associated deaths so far this year.

The department said just four of the 1,317 reported cases less than 1% were among vaccinated individuals. The figures underline the importance of vaccination as public health officials continue efforts to contain transmission.

The US Centers for Disease Control and Prevention (CDC) is expected to provide additional support to Pennsylvania to help investigate the outbreak and strengthen the public health response.

Pennsylvania health authorities have expanded vaccination outreach amid the rise in cases. According to the department’s October 21 announcement, state health department nurses had administered more than 10,000 measles, mumps and rubella (MMR) vaccine doses across the state in 2026 through pop-up clinics and state health centres. More than 56,000 MMR doses were administered by healthcare providers during September, compared with approximately 25,000 doses in a typical month.

The MMR vaccine remains the principal preventive measure against measles. Pennsylvania health officials state that two doses provide approximately 97% protection against the disease. The department has also recommended an additional early dose for infants aged six to 11 months who live in or travel to areas with sustained community transmission; this dose does not replace the two routine doses.

Measles is a highly contagious viral disease that spreads through respiratory particles and can cause serious complications, including pneumonia and brain inflammation. The Pennsylvania Department of Health has reported that nearly 20% of identified cases in the state have resulted in hospitalisation.

The rising case count highlights the importance of timely vaccination, case surveillance and public health outreach. Authorities continue to monitor transmission across affected counties and encourage residents to consult healthcare providers about vaccination status and possible exposure.