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Anyone who’s regularly smoked knows that colds and flus can hit them harder than they would a non-smoker. But people who vape could be in for the same sort of trouble, according to some new (and very preliminary) research out today. It suggests that e-cigarettes can weaken the body’s ability to fend off the flu virus, though possibly in a different way than cigarette smoke does.

Researchers at the University of North Carolina at Chapel Hill conducted a trial with three groups of human volunteers (47 in total): self-reported non-smokers, regular smokers, and regular e-cigarette users. All three groups were given a weakened form of the flu virus—the exact same kind of virus used in the nasal spray flu vaccine. In this weakened form, the virus can’t make us sick, but the body’s immune system still responds to it like a typical viral invader. Before and after the virus dose, the volunteers had their throat and nose swabbed, and a blood sample was taken from each.

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As expected, the immune systems of smokers were worse at marshaling their defenses against the flu compared to non-smokers. In smokers, there were higher levels of viral messenger RNA detected, indicating the virus was able to replicate more of itself. This change wasn’t seen among e-cigarette users, though, but others were, relative to either smokers or non-smokers.

In these users, genes and proteins involved in the innate immune system—the immediate, first-line defense against infection—and antiviral response in general, were suppressed. Another response to the flu, the production of IgA antibodies specifically tailored to the flu, was weakened in people who used e-cigarettes as well. Down the road, the authors speculated, these differences could have also dampened the body’s long-term response to the virus, known as adaptive immunity (the part of the immune system that “remembers” viruses and bacteria it’s encountered before).

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According to lead author Meghan Rebuli, a postdoctoral research associate at the University of North Carolina at Chapel Hill’s Center for Environmental Medicine, Asthma and Lung Biology, these changes could affect more than just the body’s flu-fighting prowess.

“Any dysregulation of our immune response to pathogens can potentially increase our susceptibility to viral infections and even the effectiveness of vaccines,” Rebuli told Gizmodo over the phone. “So while our study was focused on influenza, it could also be applicable to other types of respiratory infection that occur all throughout the year.”

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There are a few big caveats to these findings. The major one is that the researchers haven’t yet published their work in a peer-reviewed journal; instead, they’re previewing their study at the annual conference of the American Thoracic Society this week. That doesn’t mean the study is garbage (nor that peer-reviewed studies are always completely credible). It just means we have to treat its conclusions with some added caution. Rebuli said a peer-reviewed version of their study should be coming down the pipeline within the next month, though.

Other research has suggested a link between a weaker immune system and e-cigarette use, including a study last year showing that vaping can directly sabotage certain immune calls and increase inflammation in lung tissue—at least in the lab.

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The looming question, as with so many vaping studies though, is whether the implied effects of vaping on the body amount to significant harm. Organizations such as Public Health England have concluded that e-cigarettes, if not completely harmless, are nonetheless much less toxic than traditional tobacco cigarettes and can help smokers quit. So even if vaping could make your immune system somewhat worse during the flu season, it remains to be seen whether its effects are negligible and/or anywhere near as bad as that of smoking.

Rebuli said that because they observed more overall changes to the immune system in e-cigarette users than in smokers, there’s the possibility that vaping could hurt our ability to fight these infections more than smoking. But there still needs to be research done to confirm why that’s the case. The main takeaway from their work right now, she added, is the evidence that vaping affects the immune system in different ways than smoking does.

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Indeed, some public health experts have argued that there’s still a lot we don’t understand about e-cigarettes and their potential health risks, especially long-term. They (and the FDA) have also pointed out that the dramatic rise in teen vaping is definitely not a good thing (and might even create new smokers). And it’s young people in general, Rebuli said, who might have the most to worry about vaping’s effects on the immune system.

“I know, as a researcher, that there’s likely a place for e-cigarettes in tobacco harm reduction. But I think for youth and young adults, the increased risk for infections should be seen as a deterrent for its use, especially for someone who still has a developing immune system and brain,” she said. “But our research doesn’t directly speak to that angle, so we’ll have to wait and see.”

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This article has been updated with quotes from the lead study author. 

 

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