The United States is experiencing its highest number of measles cases in more than three decades, with outbreaks reported in several states and the first two deaths from the virus confirmed this year. As of August 20, the Centers for Disease Control and Prevention (CDC) has recorded 2,777 confirmed cases nationwide, surpassing the total for last year and marking the highest count since 1991.
Maryland recently declared a measles outbreak across three of its counties, adding 14 new cases for a 2025 total of 31. Twenty-seven of these cases, affecting unvaccinated individuals, were confirmed in the last six weeks. The affected counties are St. Mary’s with 13 cases, Carroll with eight, Cecil with five, and Charles with one. State health officials are working with healthcare professionals and local departments to manage the situation and mitigate further spread, emphasizing that the overall risk remains low for fully vaccinated individuals.
Meanwhile, an outbreak in Iowa has potentially exposed thousands of people across nearly a dozen locations. Two additional cases in southern Iowa have brought the outbreak's total to 17. Potential exposure sites include various businesses and health centers in Clive, West Des Moines, Des Moines, Ottumwa, and Bloomfield.
The first measles deaths of the year were reported in Pennsylvania, where two unvaccinated residents of Lancaster County died. These are Pennsylvania's first measles fatalities in 35 years. The state has recorded 393 cases across 28 counties in 2025. Health officials noted that measles is not widely familiar to the public due to its prior elimination in the state for decades and stressed the safety and effectiveness of the measles, mumps, and rubella (MMR) vaccine.
The vast majority of reported cases nationwide and in Pennsylvania in 2025 have occurred in individuals who have not received both recommended doses of the MMR vaccine. The CDC states that two doses reduce the risk of infection by 97%, while unvaccinated individuals exposed to the virus have a 90% chance of infection.
Measles is a highly contagious viral illness characterized by fever, cough, and a distinctive blotchy rash that begins on the face and spreads downward. It can also cause tiny white spots inside the mouth known as Koplik spots. The virus spreads through airborne droplets or direct contact and can lead to serious complications, including pneumonia, brain swelling, and damage to the immune system. Before the MMR vaccine became widely available in the 1960s, measles caused millions of deaths annually. The CDC reports that global deaths have fallen significantly since then.
Nationwide vaccination rates for measles are currently below the 95% threshold considered necessary for herd immunity. While Pennsylvania's MMR vaccination rate stands at 94.6%, Maryland's is 96%, and Iowa's is 90%. The rate of vaccination exemptions has also seen an increase.