Lancaster County measles outbreak continues to grow, and doctors are now sounding the alarm over a troubling development: several adults infected with the virus have become severely ill, requiring inpatient hospital treatment. With more than 40 cases confirmed in the county, health officials are urging vaccination as the most effective defense.

Severe Cases in Adults

A handful of very sick adults have needed inpatient care at Penn State Health Lancaster Medical Center as part of a regional outbreak. In these patients, measles has triggered a range of serious complications, including:

• Electrolyte abnormalities
• Kidney and liver dysfunction
• Blood-count abnormalities

These complications place patients at risk of organ failure, secondary infection, and bleeding. Dr. Fahmida McGann, an infectious disease specialist at the medical center, noted that adults sometimes experience more severe cases than children. Speaking at a Friday press conference on measles in Lancaster and Lebanon counties, she explained that adults often continue going to work even when ill, increasing the chance of exposure to others. Children, by contrast, are typically kept home from school when sick rather than out in public spaces like grocery stores.

A Coordinated Response

McGann was one of three Lancaster County physicians at the press conference, joined by colleagues from Penn Medicine Lancaster General Health and WellSpan. The event, held at the Lancaster State Health Center in East Lampeter Township, was organized by the state Department of Health. Officials used the occasion to stress the importance of vaccination and to outline the steps being taken by the state and healthcare providers to halt the spread.

The Growing Numbers

The outbreak has expanded steadily. Since Monday, five additional cases were confirmed in Lancaster County. Since the end of April, 41 cases have been identified there, bringing the county’s total for the year to 49.

The virus is reaching beyond Lancaster as well. This week, Northumberland County reported six cases, its first of the year. Across Pennsylvania, there have now been 84 measles cases in 2026, the majority concentrated in Lancaster and surrounding counties.

A critical detail unites all of these infections: every case has occurred among individuals who were either unvaccinated or whose vaccination status is unknown.

The Power of Vaccination

State Secretary of Health Dr. Debra Bogen used the press conference to underscore the value of immunization. She explained that two doses of the measles vaccine provide 97% protection against infection and emphasized that the vaccine has demonstrated its effectiveness for nearly half a century.

The stakes are high because measles is both potentially deadly and extraordinarily contagious. The virus can linger in a room for up to two hours after an infected person leaves. To illustrate the danger, officials shared a striking comparison: on average, 12 to 18 unvaccinated or non-immune people will catch measles from a single infected person, compared with just one to four who would catch the flu under similar circumstances.

Bogen noted that an unvaccinated person sharing a room with someone who has measles faces a 90% chance of becoming infected. She added that the Department of Health is working closely with local healthcare providers and trusted community organizations to ensure people have access to accurate information and to vaccines close to home, meeting people where they are and breaking down barriers to care.

Vaccination Efforts on the Ground

Over the past two months, the department and healthcare providers have vaccinated 430 people across the state, most of them in the Lancaster and Lebanon area. Bogen said vaccine clinics would continue for as long as they are needed but declined to reveal specific locations or times.

Protecting patient confidentiality was central to that decision. She explained that the department withholds clinic locations specifically so people can attend without media presence, ensuring they can get vaccinated with dignity and on their own terms. Information about the pop-up clinics is instead shared through word-of-mouth, flyers, and the department’s contact tracing of existing cases.

Updated Vaccine Guidance

In response to the outbreak, the department issued a health alert to healthcare providers this week with revised recommendations for affected areas. The key changes include:

• Infants in Lancaster and other counties with measles should now receive their first measles vaccine at 6 months of age, rather than waiting until age one.
• Those infants should still receive an additional dose at 12 to 15 months and another at 4 to 6 years.
• Children aged one or older who have not received any measles vaccine should get two doses spaced 28 days apart.

A Personal Plea

McGann emphasized both the safety and the broader importance of vaccination. Speaking as a physician and a mother of young, fully vaccinated children, she urged anyone eligible who is unsure of their status or has not been vaccinated to get the shot. She stressed that vaccination protects not only one’s own family but also the most vulnerable members of the community, including newborns and people undergoing treatment for cancer, organ failure, or autoimmune conditions such as lupus, sarcoidosis, and rheumatoid arthritis.

A Historic Spike

The current numbers represent a dramatic departure from recent years. In Lancaster County, the 49 cases recorded so far in 2026 stand in sharp contrast to the zero cases reported in each year from 2020 through 2025, with the last notable count being five cases back in 2019.

The statewide picture tells a similar story. Pennsylvania’s 84 cases in 2026 far exceed the 16 cases in 2025 and the handful reported in most prior years, underscoring just how unusual and serious the current outbreak has become. The figures reflect only cases among Pennsylvania residents, as tallied by the state Department of Health.