Delaware health officials formally declared a measles outbreak on Wednesday, July 22, 2026, after confirming four cases involving unvaccinated adult males in Kent County, marking the state’s first measles cluster in more than a decade and its first confirmed case since July 20.
Delaware Declares Outbreak Following Kent County Cases
The Delaware Division of Public Health announced the formal outbreak status on Wednesday after laboratory testing confirmed two additional infections, pushing the state’s total to four. According to the Centers for Disease Control and Prevention, a measles outbreak is defined as three or more cases that are connected by time and location.
All four individuals who tested positive are unvaccinated adult men residing in Kent County. Because of medical privacy restrictions, the Delaware Division of Public Health stated it is unable to provide more details about the individuals who tested positive at this time.
State health officials are conducting extensive contact tracing to identify anyone who may have been exposed to the individuals who tested positive. According to official state releases, DPH will notify people who were identified as exposed to confirm whether they have been vaccinated against measles, provide educational resources, and to recommend treatment when necessary. Officials said more information will be forthcoming if contact tracing reveals any known public exposures. Dr. Robert Rosenbaum, medical director of the Delaware EMS and Preparedness section, said officials are still working to determine how the patients contracted the airborne virus. Measles is a highly contagious disease. It's why we vaccinate for it,
he said, adding that investigators are conducting extensive contact tracing for the patients we identified, and we're watching to see if there are any additional cases.
Regional Numbers Climb Alongside a National Surge
Across the state line, Chester County’s public health director reported 13 confirmed measles cases and anticipates more, while residents expressed concern about the growing numbers. It's concerning, and I wouldn't be surprised if the numbers go up,
said Taylor Williams of Claymont, Del. Health leaders warn that measles can lead to severe complications and even death, continuing to encourage vaccination to protect vulnerable groups including infants, older adults, and people who are immunocompromised. Nationally, tracking data shows that as of July 16, 2026, 2,260 confirmed measles cases were reported in the United States in 2026 across 44 jurisdictions: Alabama, Alaska, Arizona, California, Colorado, Connecticut, District of Columbia, Florida, Georgia, Idaho, Illinois, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York City, New York State, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, Wisconsin, and Wyoming. A total of 15 measles cases were reported among international visitors to the United States. There have been 34 new outbreaks reported in 2026, and 93% of confirmed cases (2,108 of 2,260) are outbreak-associated (741 from outbreaks starting in 2026 and 1,367 from outbreaks that started in 2025). By the same week, the United States surpassed its full-year 2025 total—which saw a total of 2,289 confirmed measles cases reported across 45 jurisdictions—reaching 2,295 confirmed cases in 2026 according to Johns Hopkins University’s tracker, representing the highest annual count since the disease was declared eliminated in the country in 2000. There have been no measles deaths reported in the United States in 2026. Measles was officially eliminated from the United States in 2000, meaning transmission had been consistently interrupted for 12 months or more, and the country has held that elimination status for 26 years. With more than five months remaining in 2026 and 34 active outbreaks recorded across 44 jurisdictions, the Pan American Health Organization’s Regional Verification Commission will convene in November to assess whether the US retains its elimination designation. South Carolina, Utah and Texas have recorded some of the country’s largest outbreaks.
Vaccination Access and Public Health Guidance
In response to the cluster, Delaware health leaders have mobilized resources. Department of Health and Social Services Secretary Christen Linke Young stated, Vaccination remains the best protection against measles,
adding, I’m encouraged to see Delawareans taking action — more than 60 people received MMR vaccinations today at DPH clinics and mobile health units.
Health officials emphasize that vaccination remains the best protection against measles. Rosenbaum emphasized the effectiveness of the vaccine, noting that the immunization provides strong defense. People who are unvaccinated, pregnant, immunocompromised, or too young to be vaccinated face the highest risk of severe complications during a measles outbreak, health officials said.
Unvaccinated individuals or those unsure of their vaccination status who get exposed to a person with measles are urged to contact their primary care provider or a public health clinic to obtain an MMR vaccine. Residents are encouraged to confirm their vaccination status as well as the status of their children by visiting the DelVAX Public Portal and viewing their personal profile, or by asking their healthcare provider. Early symptoms for measles include fever, cough, runny nose and pink eye, with a rash typically occurring three to five days after symptoms begin that usually appears on the face and spreads down the body. Readers should consult qualified healthcare professionals for medical advice regarding personal vaccination decisions and exposure concerns.
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