Teenagers who smoke and vape are more likely to “entrench” tobacco use in later adolescence, academics have suggested.

Experts found that concurrent vaping in early teenage smokers could lead to persistent and heavier smoking in later adolescence.

Researchers examined concurrent smoking and vaping among the so-called “guinea pig generation” – the first generation to be exposed as adolescents to e-cigarettes as a new nicotine delivery product.

A team of US researchers analysed data over more than 1,000 teenagers from the UK and around 800 US teenagers who were smokers before the age of 15.

Some 57% of UK and 58% of US teenage smokers also used vapes.

Teenagers were regularly surveyed about their use of vapes and cigarettes up to the age of 17.

Smokers who were also vape users in their early teens were more likely to continue smoking into their late teens, the researchers said.

Some 61% of early vapers from the UK were still smoking in their late teens compared with 50% of non-vapers.

The equivalent divs for the US teenagers were 42% and 24%.

The researchers estimated that UK teenagers who smoked and vaped in early adolescence were 45% more likely to be smokers in their late teens compared to those who smoked but never vaped.

They also found that teens who smoked in early adolescence but did not use e-cigarettes were more likely to report no nicotine use in late adolescence

“Among youth who started smoking early in adolescence, early e-cigarette adopters were more likely to become entrenched into tobacco use and in heavier smoking than those who smoked but had not used e-cigarettes,” the authors wrote in the journal Tobacco Control.

They added: “Tobacco control efforts aimed at adolescents should incorporate the risks posed by e-cigarettes for early smoking youth.”

Commenting on the study, John Britton, emeritus professor of epidemiology at the University of Nottingham, said: “This study concludes that an association between vaping and continued smoking in adolescents who started smoking very young is consistent with entrenchment of smoking by vaping.

“An alternative hypothesis, that vaping by adolescent smokers is confounded with more severe nicotine addiction, does not appear to be considered. Most adolescent vaping is transient; those who persist with it are likely to be the most addicted smokers and hence those who are least likely to quit.”

Caitlin Notley, professor of addiction sciences at Norwich Medical School at the University of East Anglia, added: “This paper does not, in my view, support an ‘entrenchment theory’ as reported, since e-cigarettes are not tobacco products, although both contain nicotine. The data presented support a common liability explanation of youth experimental behaviour.”

It comes after the Department of Health and Social Care in England announced a crackdown on the illegal sale of e-cigarettes to under-18s with an “illicit vapes enforcement squad”.

The task forces would conduct test purchasing at shops and share intelligence across regional networks and local authorities, officials said.