Perhaps more important than their overall views on harm reduction are the opinions Zeller and Gottlieb have expressed about tobacco products that represent the most potential for harm reduction: e-cigarettes and vape.

For his part, Zeller has approached the segment cautiously, citing the need for strong scientific evidence to support a true reduced-harm claim.

“A hypothetical pack-a-day smoker who was otherwise unable or unwilling to quit cigarettes—if that person were to completely switch to e-cigarettes, there’s no question that person would be significantly reducing his or her risk,” Zeller admitted during a May 2016 press briefing.  “[However] ... we can’t make policy at a national and population level on the basis of hypothetical individuals or anecdotal reports of benefit.”