Smokers are “14 times more likely to develop coronavirus” according to a recent news headline.

However, this isn’t quite right. This figure doesn’t actually refer to smokers’ risk of catching the virus. Instead, the research in question found that smokers were about 14 times more likely than people who have never smoked to develop more serious COVID-19 disease when they do catch it.

Smoking damages the lungs and the blood vessels of the heart. This may be why smokers who catch coronavirus are more likely to have serious complications than non-smokers. We know that people with lung and heart disease are more at risk of complications from COVID-19.

Other early research in France quoted by The Guardian has sampled 480 people and found fewer smokers get to hospital with COVID-19, in that country, than expected. The researchers have a theory that there are specific substances in smoke, such as nicotine, that might explain this and our planning further research of better quality to test the idea.

Smoking cigarettes also means people touch their mouths frequently as they take puffs of a cigarette or pipe. Some types of smoking apparatus, such as water pipes, are typically shared. Touching your mouth frequently and sharing pipes is likely to increase the risk of catching the virus.

Where did the story come from?

The Sun’s article is based on a Public Health England (PHE) warning to smokers that they are more likely to suffer severe disease from coronavirus. Unfortunately, the Sun’s headline misreports the basis for this warning, as the research in question didn’t find that smokers are more likely to get coronavirus. Instead, it found that smokers were more likely to develop more serious COVID-19 disease.

 

What is the basis for the claim?

The press release from Public Health England (PHE) said: “The evidence clearly shows COVID-19 virus attacks the respiratory system, which explains why smokers are at greater risk” of severe respiratory disease.

The PHE press release referenced a study published in the Chinese Medical Journal at the end of February. This study reported on 78 patients treated in hospitals in Wuhan Province in China in the early days of the coronavirus outbreak.

After two weeks 67 of the 78 patients improved or stabilised while 11 deteriorated and developed more serious disease. Of those who got worse, 27% were smokers or former smokers, while only 3% of those who improved were smokers or former smokers. The researchers said that people who smoked were 14 times more likely to have deteriorated than non-smokers after taking into account other factors.

Older patients had higher temperatures or breathing difficulties on admission and were also more likely to deteriorate.

In addition, PHE said: “the repetitive hand to mouth movement provides an easy route of entry for the virus, putting smokers at greater risk of contracting COVID-19.”

PHE said these concerns give an added incentive for smokers to stop smoking.

What do trusted sources say?

The World Health Organization says: “Smokers are likely to be more vulnerable to COVID-19 as the act of smoking means that fingers (and possibly contaminated cigarettes) are in contact with lips which increases the possibility of transmission of virus from hand to mouth.

Smokers may also already have lung disease or reduced lung capacity which would greatly increase the risk of serious illness.”

Citation

  1. Liu W et al. Analysis of factors associated with disease outcomes in hospitalized patients with 2019 novel coronavirus disease. Chinese Medical Journal: February 28, 2020 doi: 10.1097/CM9.0000000000000775 https://journals.lww.com/cmj/Abstract/publishahead/Analysis_of_factors_associated_with_disease.99363.aspx (Accessed 20 April 2020)

Reading list

  1. World Health Organization, Q&A on smoking and COVID-19. 24 March 2020. https://www.who.int/news-room/q-a-detail/q-a-on-smoking-and-covid-19 (Accessed 20 April 2020)
  2. Public Health England, press release. Smokers at greater risk of severe respiratory disease from COVID-19. 3 April 2020. https://www.gov.uk/government/news/smokers-at-greater-risk-of-severe-respiratory-disease-from-covid-19 (Accessed 20 April 2020)
  3. NHS advice for people at high risk. https://www.nhs.uk/conditions/coronavirus-covid-19/advice-for-people-at-high-risk/