TAMPA, Fla.—The World Health Organization says people choosing not to vaccinate their kids is now a “global health threat.”

"Vaccine hesitancy – the reluctance or refusal to vaccinate despite the availability of vaccines – threatens to reverse progress made in tackling vaccine-preventable diseases," the World Health Organization website says.

The rising number of measles cases across the country can be argued as evidence of the problem. It was considered eliminated in the U.S. back in 2000. Florida saw 15 cases of residents getting measles in 2018, according to the Florida Health Department.

Florida health officials reported that 100 percent of the patients with measles cases during a December 2018 outbreak were never vaccinated.

Reports from the Florida Department of Health show that 86.1 percent of 2-year-olds in Florida were fully immunized in 2017.

That number is up from 2006, when the percent of fully immunized children was to 79.2.

Related: Four more measles cases in Pinellas County's first outbreak in 20 years

While most children are receiving recommended immunizations, the number of children who aren't being vaccinated by 24-months-old has been gradually increasing across the country, a report released by the Centers for Disease Control and Prevention said.

Nationally, uninsured and Medicaid-insured children were less likely to be vaccinated, according to the 2017 survey. The survey used data from the 2017 National Immunization Survey-Child and focused on children ages 19- to 35-months-old.

More: CDC monitoring measles outbreak in 21 states, including Florida

Since 2001, the percentage of unvaccinated babies and toddlers quadrupled from 0.3 percent to 1.3 percent in 2015.

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