These states won't be getting an "A" when it comes to vaccinating their pre-K kids.
In 17 states, less than 90 percent of children between the ages of 19 and 35 months have gotten recommended vaccines for diseases including measles, according to a new analysis released Wednesday by the Trust for America's Health.
Ninety percent is the national baseline goal for preschool-age kids set by federal health officials for measles, mumps and rubella (MMR) vaccinations, noted the trust, whose findings come amid a measles outbreak that has led to 102 reported cases in 14 states.
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Colorado, Ohio and West Virgina were tied for the worst vaccination rate, with just 86 percent of kids in the 19-to-35-months age group having received shots for MMR, according to the trust.
The other states that fell below the 90 percent target for preschoolers were, in descending order of vaccination rates: Missouri, Oklahoma, Alabama, Kentucky, Kansas, Oregon, South Carolina, Michigan, New Mexico, Wyoming, Virginia, Arkansas, Louisiana and Montana.
New Hampshire had the best vaccination rate, at 96.3 percent. Close behind were Washington, D.C., North Carolina and Massachusetts.
No state in the Northeast had vaccination rates for the preschool age group below 90 percent.
Nationally, the vaccination rate for kids that age stands at 91.1 percent. Federal health officials recommend that every child get an initial dose of MMR vaccine after turning a year old, and then receive a second dose between 4 and 6 years old.
Many of the infected people in the current measles outbreak were not vaccinated.
The trust pointed out that while the annual number of measles cases was below 100 for each year from 2002 to 2007, there was a spike in 2014, with more than 600 cases in 23 outbreaks.
"Sadly there is a persistent preschooler vaccination gap in the United States," said Jeffrey Levi, executive director of the Trust for America's Health. "We're seeing now how leaving children unnecessarily vulnerable to threats like the measles can have a tragic result."
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"We need to redouble our national commitment to improving vaccination rates," Levi said.
The trust noted that rates of preschoolers with vaccinations "are typically lower than for school-age children since they are not yet in the school system, which requires vaccinations for children to attend."
"Among kindergartners, 94.7 percent have been vaccinated for measles, with a high of 99.7 percent in Mississippi and a low of 81.7 percent in Colorado," the trust said.
The current outbreak, most cases of which can be traced to a Disney park in California, has sparked renewed debate over the wisdom of vaccinating kids. Health officials have urged vaccinations, but some parents avoid vaccinating their kids because of religious objections, or fears that they could lead to mental disorders such as autism.
The outbreak highlighted the fact that California, which has a 90.7 percent vaccination rate for preschool kids, nonetheless has pockets of people with relatively high rates of nonvaccinations.
"It is important that communities maintain high levels of MMR vaccination—because measles is so infectious—and especially when outbreaks are occurring around them," said Litjen Tan, chief strategy officer for the Immunization Action Coalition. "To have pockets where community immunity is below 90 percent is worrisome as they will be the ones most vulnerable to a case of measles exploding into an outbreak."
Health experts have pointed out that an often-cited study that had linked vaccinations to autism has been debunked as fraudulent.
And they've warned that low vaccination rates can lead to outbreaks of highly contagious diseases, with serious complications, including death.
"I understand that there are families that in some cases are concerned about the effect of vaccinations," President Barack Obama told NBC News earlier this week. "The science is, you know, pretty indisputable. We've looked at this again and again. There is every reason to get vaccinated, but there aren't reasons to not."
New Jersey Gov. Chris Christie and U.S. Sen. Rand Paul, R-Ky., both drew criticism when they spoke about vaccinations on Monday.
In an interview with CNBC's "Closing Bell," Paul called vaccines "a good thing" but said parents "should have some input" in deciding if their kids should get the vaccinations. He said it is "an issue of freedom."
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Paul, an opthamologist who is considering running for president next year, also said, "I have heard of many tragic cases of walking, talking normal children who wound up with profound mental disorders after vaccines."
That claim drew immediate fire from vaccination advocates for appearing to endorse the discredited link to autism.
Paul on Tuesday denied claiming that vaccines cause such disorders.
"I did not say vaccines caused disorders, just that they were temporally related—I did not allege causation. I support vaccines, I receive them myself and I had all of my children vaccinated. In fact, today I received the booster shot for the vaccines I got when I went to Guatemala last year," Paul said in the statement. He tweeted a photo of himself getting that shot.
Christie, during a visit to London, on Monday parents "need to have some measure of choice" in whether to vaccinate their kids.
After an outcry from vaccination advocates, Christie's office issued a saying, "With a disease like measles there is no question kids should be vaccinated." But he pointedly avoided questions from the media on Tuesday as his trip wrapped up.