A Preventable Resurgence: MMR Vaccination Gaps and Measles in the United States
Supervising author: Luis Isea Mercado
Underlined: presenting author
Background
Measles was declared eliminated in the United States in 2000, yet declining measles-mumps-rubella (MMR) vaccination coverage has raised concerns about renewed transmission. National kindergarten MMR coverage declined from 95.2% in 2019–2020 to 92.4% in 2025–2026, while vaccine exemptions increased. We evaluated whether state-level MMR coverage and vaccine exemption rates were associated with measles burden during the 2026 resurgence.
Methods
We conducted a cross-sectional ecological analysis using publicly available CDC data. State-level 2025–2026 kindergarten MMR coverage and exemption estimates from SchoolVaxView were linked with provisional 2026 National Notifiable Diseases Surveillance System measles data through August 29, 2026. Indigenous and imported cases were combined, and state incidence was calculated using population estimates. Spearman rank correlations evaluated associations between MMR coverage, exemption rates, and measles incidence. Jurisdictions without reportable vaccination data were excluded from corresponding analyses.
Results
Among 49 jurisdictions with reportable MMR coverage, 39 (79.6%) had coverage below 95%. MMR coverage was weakly inversely correlated with measles incidence, but the association was not statistically significant (Spearman ρ=−0.19; p=.203). Higher exemption rates showed a positive but non-significant association with incidence (ρ=0.26; p=.066). Disease burden was highly concentrated: South Carolina, Utah, Pennsylvania, Virginia, and Florida accounted for 2,003 of 2,665 (75.2%) provisional cases included in the analysis. MMR coverage in these states ranged from 87.2% to 93.6%. Utah had the highest incidence among these five states, approximately 150 cases per million residents, with 87.2% MMR coverage and a 12.7% exemption rate.
Discussion & Conclusion
The 2026 U.S. measles resurgence occurred amid widespread state-level MMR coverage below the community-immunity benchmark; however, aggregate coverage alone did not predict state-level measles burden. Cases were concentrated in a small number of jurisdictions, suggesting statewide averages may obscure vulnerable local clusters. Outbreak introduction and community-level undervaccination may influence transmission. More granular analyses may better identify populations at greatest risk and guide targeted vaccination interventions.