U.S. Measles Cases Reach 4,852 in 2026

The count is the highest since the 1989-1991 outbreak, with South Carolina accounting for 997 cases and most of its infected people unvaccinated.

Updated on Nov. 6, 2026 in Allergies

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The CDC reported 4,852 measles cases in the United States between January 1 and October 30, 2026. The figure is the highest national count since the 1989-1991 outbreak, which was largely driven by South Carolina, where 997 cases were recorded.

Why it matters

Measles is highly contagious, and the national total reflects gaps in vaccination coverage across communities. Health officials emphasize that herd immunity requires more than 95% of a community to be vaccinated.

The CDC count of 4,852 cases is the highest U.S. total since the 1989-1991 outbreak, while about 1 in 1,000 measles cases develops encephalitis, which often causes permanent brain damage. The source does not detail the geographic breakdown of cases outside South Carolina.

The players

Centers for Disease Control and Prevention (CDC)

The CDC is the federal public health agency that tracks and reports national disease data, including the 2026 measles case count.

Dr. George Haddad Jr.

Dr. George Haddad Jr. is a professor at the University of South Carolina School of Medicine in Greenville, quoted in coverage of the measles outbreak.

The details

The South Carolina outbreak, which accounted for 997 cases, ended April 26 after an aggressive vaccination campaign, and more than 93% of those infected there were unvaccinated. Two doses of the MMR vaccine offer the strongest protection against measles.

1989-1991: Previous U.S. measles outbreak with a higher case count.
April 26, 2026: South Carolina measles outbreak ended.
October 30, 2026: End of the CDC's reported case count period.

Big Picture

The 4,852 cases reported in 2026 are the highest national total since the 1989-1991 U.S. measles outbreak. That earlier episode set the benchmark against which current case levels are now measured.

Two doses of the MMR vaccine offer the strongest protection against measles, a point that matters for parents and adults deciding on vaccination. Encephalitis, which develops in about 1 in 1,000 measles cases, often causes permanent brain damage.

The takeaway

Staying current on the MMR vaccine schedule is the most direct way individuals can reduce their own measles risk. Community vaccination levels above 95% are needed to protect people who cannot be vaccinated.