Significant Decline in MMR Vaccination Rates Linked to COVID-19 Pandemic

New Data Reveals Alarming Trends in Vaccination Rates

A troubling new dataset from researchers at Johns Hopkins University has identified a sharp decline in the measles-mumps-rubella (MMR) vaccination rates among children in the United States, a trend that has emerged since the onset of the COVID-19 pandemic. The analysis, covering 2,066 counties, highlights that a staggering 78% of these counties—1,614 in total—reported reductions in vaccination rates.

Prior to the pandemic, the average county-level vaccination rate was recorded at 93.92%. However, post-pandemic analysis indicates a drop to 91.26%, reflecting an average decline of 2.67%. This decline moves the vaccination rates further away from the critical 95% threshold necessary for herd immunity, a level that is crucial for limiting the spread of measles.

Interestingly, only four states—California, Connecticut, Maine, and New York—showed increases in their median county-level vaccination rates among the 33 states studied. This localized improvement stands in stark contrast to the overall national trend of declining vaccine uptake.

Current Measles Outbreaks Raise Concerns

The urgency of the findings is underscored by the fact that over a thousand measles cases have been reported this year in the U.S. This marks one of the highest counts recorded in more than three decades, overshadowed only by the spike seen in 2019. Alarmingly, most of the cases this year have occurred among unvaccinated children, emphasizing the stakes involved in maintaining adequate vaccination coverage.

Dr. Lauren Gardner, the senior author of the study and director of the Center for Systems Science and Engineering at Johns Hopkins University, emphasized the importance of this new, high-resolution, open dataset. She stated, "This critical resource will help explore and understand the country's vaccination landscape and its implications for the risk of measles spread." Gardner's expertise in data modeling, which notably contributed to the globally recognized COVID-19 dashboard, informs the need for precise data in addressing these health challenges.

Consolidating the Data for Better Insights

The county-level vaccination data serves to complement existing state and national data provided by the Centers for Disease Control and Prevention. It confirms the widespread decline in MMR vaccination rates while illustrating the significant variability in vaccine administration patterns both within and across states.

The research team meticulously gathered county-level data on 2-dose MMR vaccination rates for kindergarteners from 2017 to 2024, utilizing state health department websites where feasible. Their dataset includes immunization records from at least one year for 2,237 counties spanning 38 states, providing a comprehensive overview of vaccination trends.