(CBS/AP) Have parents given the cold shoulder to immunizations for their kids? In eight states, more than 1 in 20 public school kindergartners fail to get all the vaccines required for attendance, according to a new Associated Press analysis. That apparent trend has health officials worried about outbreaks of diseases that once were all but eliminated.
The analysis found that more than half of states have seen at least an uptick in the rate of exemptions in the past five years.
It's "really gotten much worse," said Mary Selecky, secretary of health for Washington state, where 6 percent of public school parents have opted out.
Reasons for skipping school shots vary. Some parents doubt that the vaccines are essential. Others fear vaccines are risky. Some find it easier to check a box opting out than getting the shots and taking care of the required paperwork. Still others are ambivalent, believing in older vaccines but questioning newer shots against, say, chickenpox.
Some parents worry about the number of shots. By the time most kids are 6, they'll have been jabbed with a needle about two dozen times - with many of those shots given in infancy. The cumulative effect of those shots hasn't been studied thoroughly, some parents say. But few serious problems have turned up despite years of vaccinations, and studies have shown no link between childhood vaccines and autism.
Overall, childhood vaccination rates remain high, at 90 percent or above for several vaccines, including those for polio, measles, hepatitis B and even chickenpox. In many states, exemptions are filed for fewer than 1 percent of kids entering school for the first time.
Health officials have not identified an exemption threshold that would likely lead to outbreaks. But as they push for 100-percent immunization, they worry when some states' exemption rates are climbing over 5 percent. The average state exemption rate has been estimated at less than half that.
Parents may think it does no harm to others if their kids skip some vaccines, but health officials say they're putting others at risk. No vaccine is totally effective. If an outbreak begins in an unvaccinated group of children, a vaccinated child may still be at some risk of getting sick.
And while it seems unlikely that diseases like polio and diphtheria could mount a comeback to the U.S., CDC immunization expert Dr. Lance Rodewald said it could happen.
For its review, the AP asked state health departments for kindergarten exemption rates for 2006-07 and 2010-11. The AP also looked at data states had previously reported to the federal government. (Most states lack data for the 2011-12 school year.)
Exemption seekers are often middle-class, college-educated whites, but there is often a mix of views and philosophies. Exemption hot spots like Sedona, Ariz., and rural northeast Washington have concentrations of both alternative medicine-preferring as well as government-fearing libertarians.
What many of exemption-seeking parents share, however, is a mental calculation that the dangers posed by vaccine-preventable diseases are less worrisome than the possible harms from vaccine. Or they just don't believe health officials, putting more stock in alternative sources - often discovered through Internet searches.
Parents say they'd like to decide which vaccinations their children get, and when. Health officials reply that vaccinations are recommended at an early age to protect children before they encounter a dangerous infection. "If you delay, you're putting a child at risk," said Gerri Yett, a nurse who manages Alaska's immunization program.
Some parent groups have pushed legislators to make exemptions easier or do away with vaccination requirements altogether. The number of states allowing philosophical exemptions grew from 15 to 20 in the last decade.
Some in public health are exasperated by the trend. As another University of Arizona researcher, Kacey Ernst, put it, "Every time we give them evidence (that vaccines are safe), they come back with a new hypothesis" for why vaccines could be dangerous."