Models project lives saved if smokers switch to vaping

Simulation studies in the United States, Germany and Russia project that switching from cigarettes to nicotine vaping products could prevent premature deaths and save life-years. The estimates are not guarantees: they depend on assumptions about vaping’s relative risks, how many smokers switch and whether non-smokers take up vaping.

How the model estimates possible benefits

One tool used for these projections is David Levy’s Smoking and Vaping Model (SAVM), a cohort-based simulation adapted for several countries. It compares a baseline without vaping, built from population, mortality and smoking-prevalence trends, with a scenario in which nicotine vaping products displace cigarettes. The difference between the scenarios represents deaths and life-years projected to be averted.

The original US application, published in Tobacco Control in 2017, projected outcomes through 2100. In its optimistic scenario, reducing smoking prevalence to 5% through vaping was projected to prevent 6.6 million premature deaths and save 86.7 million life-years.

The comparison covered 2016 to 2100 and used different assumptions about the relative harms of e-cigarettes and their effects on initiation, cessation and switching. Even the pessimistic scenario, which assumed greater youth uptake of vaping and higher relative risk, projected 1.6 million premature deaths prevented and 20.8 million life-years saved.

The model projected the greatest gains for younger smokers, who have more years of life ahead. For a 15-year-old smoker in 2016, it estimated an average gain of half a year in life expectancy. That is a population-wide average; the article notes that individuals who avoid a smoking-caused cancer or heart attack could gain much more.

Results vary across countries and assumptions

Later applications of the model produced estimates for other countries. For Germany, it projected 4.7 million life-years saved and 300,000 deaths avoided by 2060. A separate simulation for Russia tested a wider range of assumptions and found positive results in 88% of scenarios, with life-years saved reaching up to 38.5 million over 80 years.

Three factors shape these projections. The first is vaping’s relative risk: the models typically assume it carries between 5% and 40% of the harm of smoking. The article also reports that UK health authorities have put long-term vaping risk at under 5% of smoking’s risk.

The second factor is how many smokers switch. These are conditional forecasts: the projected number of deaths avoided depends on the share of smokers who move to vaping. The article identifies regulation, price and how easy governments make it for smokers to access vaping products as factors that may affect switching.

The third factor is youth initiation. If non-smokers, particularly teenagers, take up vaping and some go on to smoke, the projected net benefit is reduced. The article describes this as the most contested input and says it accounts for much of the difference between optimistic and pessimistic scenarios.

Taken together, the US, German and Russian model results suggest a wide range of possible outcomes, from hundreds of thousands to several million lives saved over coming decades. The projections depend on how quickly switching occurs and how the models account for vaping’s own risks.

The article argues that, given smoking’s death toll, even the pessimistic projections represent a substantial potential public-health benefit. It also criticises efforts to make vapes harder to access or use. The estimates, however, remain projections based on specified assumptions rather than a single certain outcome.