The Pennsylvania measles outbreak has passed 1,000 confirmed cases, with health officials reporting 1,004 infections, 198 hospitalisations and five deaths across 39 counties this year.
The outbreak, which began in late April in communities west of Philadelphia, has spread most extensively in Chester and Lancaster counties. Pennsylvania now has the highest measles case total of any US state, according to the state Department of Health.
Officials are warning that the confirmed figure may not reflect the full scale of transmission. Jeanne Franklin, Chester County’s health director, said some families had reported that several members were ill when health workers contacted them during disease investigations.
“It is still increasing, it is spreading. Measles is fast that way,” Ms Franklin said.
Vaccination campaign expands across Pennsylvania
The state has responded by widening access to the measles, mumps and rubella (MMR) vaccine through pop-up clinics, local appointments, state health centres and home visits. Nearly 200 clinics have been held in affected communities, with more than 5,700 vaccinations administered at those sites since the outbreak began.
Across Pennsylvania, state health centre staff have given more than 8,800 MMR doses this year. More than 53,000 doses were administered statewide in September alone, following over 49,000 in August.
Health officials say the vaccine remains the most effective protection against measles and is 97 per cent effective at preventing infection after two doses. They are also urging some adults to have their measles antibodies checked and to consider revaccination if they are not protected.
Dr Michael Cirigliano, of the Perelman School of Medicine at the University of Pennsylvania, said he advised patients in certain age groups to undergo antibody testing where their immunity was uncertain.
The Pennsylvania Department of Health has also briefed more than 1,000 healthcare professionals and school nurses, while issuing guidance on treating young children and managing infections during pregnancy.
Nationally, the Centers for Disease Control and Prevention had recorded 3,887 confirmed measles cases in the United States by 1 October, including 745 in Pennsylvania in its resident case table. The state’s later total reflects subsequent reporting and updates from Pennsylvania health officials.
Measles is highly contagious and can spread through the air or from contaminated surfaces. Health authorities say about 95 per cent vaccination coverage is needed in a community to maintain protection and bring the outbreak under control.
Officials have cautioned that the number of infections could rise further, particularly in rural areas where cases may be less likely to be diagnosed or formally reported.
