“The flavor ban is reactive,” said Dr. Sharon Levy, an adolescent addiction expert at Boston Children’s Hospital. “It’s just a matter of time until companies figure out a way around it. We have to be more proactive.”

Dr. Levy said that just about every patient referred to her practice also vapes. Vaping has become normalized for teenagers, she added.

“Kids say that these devices have all the pleasures of cigarettes without the harm,” said Dr. Levy. “It’s like a cup of coffee for them.”

She is particularly worried about the amount of nicotine that her patients are absorbing. She is even seeing cases of nicotine toxicity.

The main results are similar to preliminary figures released from a separate survey last week by Mr. Azar. The early results from the National Tobacco Youth Survey indicated an increase to 27.5 percent from 20 percent last year in e-cigarette use among teenagers asked if they had vaped in the last 30 days.

In the survey released Wednesday afternoon, students were asked for the first time if they had vaped on at least 20 days within the last 30 days, underscoring concerns that teenagers are becoming addicted to nicotine and the effects that the substance can have on the developing brain. Twelve percent of 12th-graders said they had vaped that frequently,

7 percent of 10-graders and 2 percent of 8th-graders.

“Current efforts by the vaping industry, government agencies, and schools have thus far proved insufficient to stop the rapid spread of nicotine vaping among adolescents,” the researchers said. “Of particular concern are the accompanying increases in the proportions of youth who are physically addicted to nicotine, an addiction that is very difficult to overcome once established. The substantial levels of daily vaping suggest the development of nicotine addiction.”