The disease was officially declared to be eliminated in the U.S. in 2000. There’s little mystery about what’s changed since 2020. Vaccination rates went down during the pandemic, and they’ve yet to return to the level considered necessary to prevent outbreaks.
Measles is one of the world's most contagious viruses. Children are especially vulnerable; if an unvaccinated child comes into contact with an infected person, there’s a 90 percent chance they will contract the disease. Since 2020, vaccination rates among kindergarten-aged children have dropped below the 95 percent recommended by the public health community in most states. Only 10 achieved this during the 2024-2025 school year.
Some scientists believe concerns about the COVID-19 vaccine compounded parental hesitancy about childhood vaccinations. For example, a not-insignificant 4 in 10 Republicans believe the vaccine killed more people than the virus. Trust in public officials has decreased among both parties, though less so for Democrats. The hollowing out of federal agencies that help guide disease prevention, combined with turmoil and confusion over childhood vaccination schedules, are additional disruptions to past practice.
The rates represented in the map below, which the Centers for Disease Control and Prevention (CDC) draws largely from census data, represent vaccination of kindergarten-age children. For a recent study published in the journal Nature, researchers looked at vaccination rates among children five and under. Thirty percent of 2025 measles cases were in this age group; 90 percent of those who became ill were unvaccinated. Drawing on data from crowdsourced reports of infection and an AI model developed by Google, they estimated median county-level coverage in this age group to be just over 71 percent.
State officials in South Carolina announced this week that the measles outbreak there —the country’s largest in decades — has ended. An uptick in vaccination rates is believed to be a significant factor in this, a change of attitude some public health officials attribute to a “collective remembering” of the seriousness of the disease.
Hover over a state in the map below to see the CDC’s estimate of its measles vaccination rate.
