Why It Matters
Maryland health officials have declared a measles outbreak affecting three counties, with all cases since mid-July occurring among unvaccinated individuals. The outbreak underscores ongoing vaccination disparities and the virus’s rapid spread potential among populations without immunological protection.
What Happened
State health authorities confirmed 31 measles cases across Maryland in 2026, with 27 of those cases occurring since July 15. The outbreak centers on St. Mary’s, Carroll, and Cecil counties, though cases have also appeared in Charles, Anne Arundel, Baltimore, and Prince George’s counties.
St. Mary’s County accounts for the largest cluster, with 13 confirmed cases. Carroll County has reported 8 cases, while Cecil County has documented 5. A single case emerged in Charles County. Four additional cases were confirmed in the months before July 15 in Anne Arundel, Baltimore, and Prince George’s counties.
Among the 27 cases confirmed since July 15, all occurred in unvaccinated individuals. Investigators have found no evidence of widespread community transmission; most infections traced to household contact with infected persons. No public exposures have been identified in connection with current cases.
In response, Maryland health officials have intensified vaccination efforts. More than 24,000 measles-mumps-rubella vaccines have been administered since July 1, 2026, as part of the public health response. Across the calendar year, the state has administered more than 106,000 MMR doses.
By the Numbers
31 — total confirmed measles cases in Maryland in 2026
27 — confirmed cases since July 15, 2026
13 — cases in St. Mary’s County
8 — cases in Carroll County
5 — cases in Cecil County
10–13 — estimated number of unvaccinated individuals who could contract measles from one infected person
90% — likelihood of infection if exposed to measles without vaccination protection
1%–2% — measles mortality rate
24,000+ — MMR vaccines administered since July 1, 2026
Zoom Out
Measles, declared eliminated in the United States in 2000, has resurged in pockets where vaccination rates fall below critical thresholds. Each infected individual can transmit the virus to between 10 and 13 unprotected people, according to health data. The virus carries documented health risks: approximately 1 in 100 children infected develop measles-related pneumonia, and the disease carries a mortality rate between 1% and 2%.
The American Academy of Pediatrics recommends the first MMR dose at 12–15 months of age and a second dose between 4 and 6 years. In outbreak settings, early vaccination at 6–11 months is considered. Maryland’s outbreak reflects a national pattern of measles resurgence tied to declining immunization rates in specific communities.
Vaccination Status and Risk Assessment
State health officials have stressed that vaccinated individuals face minimal risk. “Overall risk remains low if you are fully vaccinated,” according to a statement from state health leadership, as first reported by the Maryland Matters. The concentration of cases among unvaccinated persons highlights the effectiveness of two-dose MMR vaccination schedules in preventing infection.
One state epidemiologist emphasized the contagion rate: “For every person that is infected with measles, for those without protection, so unimmunized individuals, on the order of between 10 and 13, could get or would get that illness from the one person,” illustrating why vaccination coverage matters in containing spread.
What’s Next
Maryland health authorities will continue monitoring case counts and vaccination uptake across affected and surrounding counties. Clinicians have been advised to consider early MMR vaccination for children in outbreak areas and to maintain heightened surveillance for suspected measles cases. The state expects vaccination administration to remain elevated as communities work to increase immunity levels above the threshold needed to interrupt transmission chains.