Table 3.

Summary of results of the included studies by regulation type and outcome*

Policy interventions	Number of studies by effectiveness (positive / negative / mixed)
	Current use	Other outcome
Flavour restrictions	4 / 0 / 1	8 / 0 / 0
Indoor vaping restrictions	1 / 4 / 0	-
Taxation	3 / 1 / 0	2 / 2 / 0
Comprehensive bans	-	2 / 1 / 0
Age restrictions	4 / 5 / 1	1 / 0 / 1
Licensing requirements	1 / 0 / 0	-
TPD	0 / 2 / 0	7 / 0 / 2
Advertising restrictions	-	3 / 1 / 0
Packaging	-	0 / 1 / 0

TPD – the Tobacco Products Directive

*This table shows the number of studies that supported the effects / did not support the effects / showed mixed results for the effects of policies on reducing electronic nicotine product (ENPs) use or preventing harms from ENPs.