ATLANTA — Georgia saw some of the worst declines among kindergarten vaccination rates of any state in the country this decade, a new report outlining CDC data shows.

Data compiled from the Centers for Disease Control and Prevention SchoolVaxView resource guide by the company Health Testing Centers showed the Georgia kindergarten population experiencing a 6.4 percent decline in vaccinations for MMR (measles, mumps, rubella), DTaP (diptheria, tetanus, pertussis), hepatitis B and polio from 2009-18.

That ranked as the single-worst decline among the 42 states that reported full data.

The decline is all the more stark because in 2009, Georgia had one of the best-vaccinated kindergarten populations in the country. 

The CDC data indicates 99.9 percent of Georgia kindergartners in 2009-10 had been vaccinated for DTaP and 99.6 percent were vaccinated for MMR - numbers that were among the top-two in the country in both cases. 

By 2018-19, that number dropped to 93.6 in both instances - placing Georgia in the bottom half of states.

Confirmed measles cases have dotted the Atlanta area this year - including most recently in Cobb County, where an outbreak resulted in 11 confirmed cases, more than in the previous decade combined.

RELATED: Health officials identify source of measles outbreak in Cobb County

On Monday the Georgia Department of Public Health said it had identified the source of that outbreak, linking it to five previously unreported cases in one family in early October.

“Measles vaccination (MMR) is safe and effective and prevents outbreaks,” said Kathleen E. Toomey, M.D., M.P.H., DPH commissioner. “The current measles outbreak in Georgia is small compared to other outbreaks documented around the country. However, the toll even a single case of measles takes goes well beyond physical illness - impacting economies, work forces, education, health care systems, and creating a public health burden to protect vulnerable populations.”

Health officials have warned that misinformation - much of it spread online - is contributing to declining vaccination rates and increasingly recurring outbreaks of illnesses that were once thought eradicated.

Earlier this year, the country experienced its worst measles outbreak in 25 years, and more than 1,200 cases have been reported nationally this year.

RELATED: Thousands of US kindergartners unvaccinated without waivers

"It (the high numbers of cases) is actually alarming, because measles was almost eliminated in the world," 11Alive medical correspondent Dr. Sujatha Reddy said last week. "And there’s no question that because we have pockets of unvaccinated people, we’re seeing this disease come back, and come back strong."

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