Three out of four Arizona toddlers have received a recommended series of vaccinations against measles, polio and other diseases, according to estimates released Thursday by the Centers for Disease Control and Prevention.
Arizona still was slightly below the national average and ranked 37th among all 50 states and the District of Columbia when it comes to the series covering measles, mumps and rubella, polio, hepatitis B, chicken pox and diptheria, tetanus and pertussis.
The CDC's survey, covering 2007, involved children born between January 2004 and July 2006.
It found that 75.2 percent of toddlers in Arizona had received the vaccines, up from 70.6 percent in the 2006 survey.
Maryland had the highest rate at 91.3 percent; Nevada was lowest at 63.1 percent.
The national average was 77.4 percent.
Kathy Fredrickson, office chief for the Arizona Department of Health Services' Arizona Immunization Program, said she was pleased with the increase. She said officials are unsure why Arizona ranks behind other states.
"If we knew the answer, we would do something about it," she said.
But Fredrickson said Arizona's growing population might have something to do with the way the statistics are gathered.
"We're one of the fastest-growing states; it's hard to keep track of all those kids," she said.
Debbie McCune-Davis, program director of the nonprofit Arizona Partnership for Immunization, said Arizona faces an unusual challenge because so many residents come and go. Their medical records don't always follow them, she said.
"We're not like a little town in the Northeast where children are going to the same doctors' offices that their parents went," McCune-Davis said.
She attributed Arizona's increase in immunizations to greater availability of health care and health insurance for children.
Frederickson expects Arizona's rate to continue to climb.