Recent Data Highlights Decline in MMR Vaccination Rates Across the United States

A new comprehensive county-level dataset from Johns Hopkins University has revealed a concerning trend: a decline in the measles-mumps-rubella (MMR) vaccination rates among children throughout the United States since the onset of the COVID-19 pandemic. Analyzing data from 2,066 counties across 38 states, researchers found that approximately 78% of these counties experienced drops in vaccination coverage. Overall, the average county-level MMR vaccination rate decreased from 93.92% before the pandemic to 91.26% afterward, marking an average decline of 2.67%. This reduction pushes vaccination levels further away from the 95% threshold generally considered necessary to achieve herd immunity and prevent the spread of measles. Notably, only four states—California, Connecticut, Maine, and New York—reported an increase in their median county vaccination rates. The findings are published in the Journal of the American Medical Association (JAMA). This decline in vaccination coverage is particularly alarming given recent reports of over a thousand measles cases in the current year, making it the highest in over three decades excluding 2019. Most of these cases have occurred in unvaccinated children, emphasizing the ongoing risk posed by declining immunization rates. Senior author Lauren Gardner, director of Johns Hopkins’s Center for Systems Science and Engineering, emphasizes that this high-resolution dataset offers vital insights into the country’s vaccination landscape and its implications for disease spread. The research draws from her extensive experience leading COVID-19 data collection efforts and provides a critical resource for understanding regional vaccination patterns and risks. The data corroborate earlier findings from the CDC, revealing widespread declines post-pandemic and significant heterogeneity within and across states. The team gathered county-level 2-dose MMR vaccination data for kindergarteners from various state health websites, which enhances understanding of local vaccination trends and gaps. Overall, these findings highlight the urgent need for targeted efforts to boost vaccination rates and prevent potential outbreaks of vaccine-preventable diseases.