Almost half of the people who followed Juul Labs Inc on Twitter were not old enough to legally purchase e-cigarettes in the United States, according a study published on Monday. Researchers analysed data collected in April 2018 on all public followers of Juul´s Twitter account with at least one public Tweet. About 45 percent of the individuals who followed Juul were 13 to 17 years old, according to the study in JAMA Paediatrics, published online on Monday. In the study, only 19 percent of Juul´s Twitter followers were at least 21. These findings from more than a year ago may not reflect what is happening on social media today. The study also was not a controlled experiment designed to prove whether or how following Juul on social media directly impacts vaping habits. Other research has linked teen vaping to an increased risk of smoking traditional cigarettes.