The Role of Vaccine Decline: Why Measles is Back

Measles outbreaks don't just happen randomly—they occur when vaccination rates drop below the herd immunity threshold of 95%. That's the percentage of people who need to be vaccinated to prevent widespread outbreaks.

Unfortunately, vaccination rates have been steadily declining, especially in certain states where policies have weakened school vaccine requirements.

The following visualizations highlight how these declining rates are directly fueling the rise in measles cases.

Kindergarten Vaccination Rates (2009–2024)

The takeaway: The percentage of kindergartners receiving the MMR vaccine has dropped nationwide, with some states falling well below the critical 95% threshold.

2009–2015: MMR vaccination rates remained steady around 95%.
2016–2019: A slight decline began, as misinformation campaigns gained traction.
2020–2022: The COVID-19 pandemic disrupted routine childhood vaccinations.
2023–2024: Some states are now below 90%, increasing the risk of outbreaks.

State-by-State Vaccine Decline

The takeaway: Not all states are equally at risk—some have seen much sharper declines in vaccination rates due to policy changes and misinformation.

States that have maintained strong vaccine mandates (e.g., California, New York) have kept rates near 95%.
States that have expanded vaccine exemptions (e.g., Texas, Florida, Idaho) have seen the sharpest declines.
Some communities have rates below 85%, well below the safety threshold.