In a commentary by the director of the National Institutes of Health (NIH), it is claimed that electronic cigarettes cause respiratory infections and asthma. According to the NIH director:
"E-cigarettes come with their own health risks, including lung inflammation, asthma, and respiratory infections."
The Rest of the Story
There is clinical evidence that vaping causes lung inflammation, so that part of the statement is supported by evidence. Specifically, vaping can cause lung irritation, leading to short-term increases in airway resistance as measured by sensitive technology, although not apparent by routine spirometry. Whether this acute irritation has consequences for the risk of actually developing chronic respiratory disease is not known.
However, when it comes to the claim that e-cigarettes cause asthma and respiratory infections, the story is quite different.
There is no clinical or epidemiological evidence that e-cigarettes cause either asthma or respiratory infections. There is one cell culture study which found an increased susceptibility to infection of respiratory epithelial cells. However, there is not a single clinical or epidemiological study I am aware of that documents an increase in the risk of respiratory infection due to vaping. Nor is there a single clinical or epidemiological study that documents an increased risk of asthma due to vaping.
In fact, on the contrary, there is evidence that switching from smoking to vaping actually decreases asthma symptoms and improves lung function and that it may reduce the risk of respiratory infections and pneumonia. Moreover, propylene glycol - the excipient in most e-liquids - is known to have bactericidal properties. In one study, smokers who switched to vaping reported a decreased incidence of respiratory infections.
That vaping can cause respiratory irritation is a fact. But the claim that vaping causes asthma and respiratory infections is what in today's lexicon might be referred to as an "alternative fact."