In contrast, 6 percent of adults have tried e-cigarettes, according to a different CDC survey done in 2011.
Children still are more likely to light up regular cigarettes, though teen smoking rates have dropped in the past decade. More teens now smoke marijuana than tobacco, surveys have found.
But health officials worry e-cigarettes could re-ignite teen cigarette use. They point to a finding in the study that 20 percent of middle school e-cigarette users had never tried conventional cigarettes. When the same question was asked of high school students, only 7 percent had never tried regular smokes.
That suggests many kids experiment with the electronic devices and move on to cigarettes by high school, said CDC Director Dr. Tom Frieden.
"In effect, this is condemning many kids to struggling with a lifelong addiction to nicotine," he said.
Kurt Ribisl, a University of North Carolina tobacco policy expert, was a bit more restrained, saying the results "don't prove that e-cigarettes are a gateway to smoking cigarettes." Another study would be needed to more clearly establish the link, he added.
He said the results may fuel the Food and Drug Administration's plans to eventually regulate e-cigarettes.
Some makers of e-cigarettes said Thursday that they supported regulations that keep the devices out of kids' hands. But some are wary of steps that might affect adult buyers.Future regulations shouldn't "stifle what may be the most significant harm reduction opportunity that has ever been made available to smokers," Murray Kessler, chief executive of Lorillard Inc., the nation's third-biggest tobacco company and owner of Blu Ecigs, said in a statement.