Study doesn’t say most vapers are 17% more likely to transmit Covid

“Vapers with Covid-19 up to 20% more likely to transmit it than infected non-smoker [...] Vapers who have Covid-19 are up to 17% more likely to transmit the virus, spreading it in clouds of smoke”.

“Vapers up to 17% more likely to spread coronavirus because it gets blown around when they breathe out”.

The findings of a study looking at the relative risk of someone transmitting Covid-19 through exhalation while smoking an e-cigarette (vaping) have been reported by both The Telegraph and MailOnline. Both reported that vapers are up to 17% more likely to transmit Covid-19. 

The study actually found that, for the vast majority of UK vapers, the increased risk of transmission is around 1% compared to someone who is just resting and breathing. This is considerably lower than the increased risk of transmission from talking or coughing. Concerns over the media reporting of this study have been shared on Twitter, including by the lead author of the study.

The study—which has not yet been peer reviewed—used a mathematical model to look at the risk of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets exhaled along with e-cigarette aerosol (ECA). It said that 90% of vapers in the UK use low powered vaping devices. If a low intensity vaper with Covid-19 was to exhale ECA in an indoor setting (like a home or restaurant), the paper estimated that the added risk to bystanders compared to someone simply breathing was just 1% higher. 

For the minority who are classed as high intensity vapers, which is usually associated with using a rarer advanced tank system e-cigarette and can create large vapour clouds, the paper estimated the added risk rose to between 5% and 17%. 

The top of this estimate, 17%, is what both The Telegraph and MailOnline used in their reports, particularly in the headlines and subheadings, without making sufficiently clear that this would be the minority of vapers. Although both news outlets did include the 1% figure in their pieces, much more emphasis was given to the larger figures. The figure of 20%, used in The Telegraph’s headline, does not appear in the study.

The paper also found that vaping carried lower risks than other activities. It said that, compared to breathing, the increased risk of being around someone speaking without vaping is between 40 and 90%, while the increased risk of being near someone speaking and coughing is 200%. 

The study said that vaping “will add only a minuscule additional risk to those risks already existing from continuous breathing or talking in indoor or socially shared spaces without universal wearing of face masks, which offer fairly effective protection against pathogen contamination by infected persons, but also provide reasonably good protection for bystanders exposed to emissions from people infected who are not wearing a mask.

“Therefore, as far as protection against SARS-CoV-2 virus is concerned, vaping in a home scenario or in social spaces does not require extra interventions besides those already recommended for the general population: social distance and wearing face masks.”

The study also notes that “while there is currently no factual evidence that pathogens have been spread through this route,  it is entirely plausible that this should occur.”

UK Government advice, published in May, states that there is “currently no evidence that Covid-19 can be caught from passive exposure to e-cigarette vapour, but in the absence of evidence we recommend that vapers avoid exhaling clouds of vapour in the presence of others.”