Coverage of rising U.S. measles cases is often coupled with news about Americans’ declining confidence in vaccines.

Scientists are quick to differentiate between correlation — when two things are related but not necessarily dependent on one another — and causation, when one thing causes another.

But when it comes to vaccine trust and vaccination rates, data shows in the U.S., parents are less likely to fully vaccinate their kids when their beliefs call into question whether vaccines are safe, effective or necessary.

“There’s a correlation there,” said Lunna Lopes, a senior survey manager at the health policy research group KFF. “That relationship remains significant even when we control for factors like age, education and partisanship.”

Falling vaccination rates have predictable consequences. Cases of measles — a disease declared “eliminated” in the U.S. in 2000 — have been rising in recent years. The U.S. has already reported nearly 500 more cases of measles in the first eight months of 2026 than in all of 2025, according to Centers for Disease Control and Prevention data.

The exact factors driving upticks in such vaccine-preventable illnesses aren’t easy to pin down, but here are five charts that tell some of the story.

United States vaccination trends 

During the 2025-26 school year, there was a 0.1% overall drop in vaccination coverage among students entering kindergarten, the CDC reported.

The decline follows an overall trend of falling vaccination coverage among kindergartners that has been largely consistent regardless of the type of vaccine since the COVID-19 pandemic.

Even small percentage declines leave thousands of children unprotected, health experts say. For the 2025-26 school year, about 280,000 kindergartners attended school without documented completion of the measles, mumps and rubella vaccine series, or MMR, for example.

Robin Mejia, a biostatistics professor at the University of Washington’s School of Public Health, said the nation’s 0.1% overall vaccination decline doesn’t hit every place evenly.

“There’s going to be huge drops in some regions and in some school districts, and hardly any drops in others,” Mejia said. “That’s what allows things like measles to spread.”

CDC data showed that during the 2025-26 school year, a growing share of parents requested their children be permitted to attend school without being fully vaccinated.

Requests for exemptions from vaccine requirements for medical reasons have remained relatively consistent for years, but requests for non-medical exemptions have increased consistently since the 2020-21 school year.

During the same period, the overall percentage of children vaccinated against measles, mumps and rubella generally decreased.

Epidemiologists say 95% of people need to receive the MMR vaccine to achieve herd immunity, preventing community transmission. During the 2025-26 school year, just 10 states were at or above that threshold.

So far in 2026, there have been over 2,700 measles cases in the U.S. In 94% of those cases, the person was unvaccinated or their vaccination status was unknown, the CDC reported.

In 2025, two school-aged children and one adult died of measles. All were unvaccinated.

On Aug. 25, authorities announced “two measles-associated deaths” in unvaccinated people in Pennsylvania. One was a newborn who a coroner said died of an internal hemorrhage and traumatic spleen rupture; the coroner found evidence of the measles virus in the baby’s lung tissue, but it’s unclear exactly what role the measles infection played in the death.

Belief in falsehoods about vaccines is linked to decisions to delay, skip them 

Since 2015, the Vaccine Confidence Project has found that support for statements such as “vaccines are safe” and “vaccines are compatible with my beliefs” has fluctuated.

As of 2023, belief in the statements “vaccines are important for children to have,” “vaccines are safe,” and “vaccines are effective” had fallen compared with 2015.

It’s difficult to say exactly what role vaccine myths and falsehoods ultimately play in vaccination decisions, but in May 2026, KFF found correlation between parents reporting belief in false statements about vaccines and their decisions to skip or delay some vaccines.

Parents who said they avoided or postponed getting their kids fully vaccinated were about twice as likely as other parents to say they believed certain vaccine falsehoods were “definitely” or “probably true.”

KFF’s Lopes said relatively small shares of people believe that these sorts of vaccine myths are definitely true.

“But what we do see is that a lot of people fall in what we call this kind of muddled middle,” she said. Those people might not outright reject or accept false statements about vaccines, and instead might report them as either “probably true” or “probably false.”