A University of Oxford-led study analyses observational and genetic data on smoking and COVID-19


Smokers are 80% more likely to be admitted to hospital with COVID-19 than non-smokers, according to a University of Oxford-led study.

Observational data were analysed alongside hospital coronavirus test data and UK Biobank genetic information for the first time, and the findings were published in Thorax.

The data cover 421,469 people overall. Of these:

  • 3.2% took a polymerase chain reaction swab test

  • 0.4% of these tested positive

  • 0.2% of them required hospitalisation for COVID-19

  • 0.1% of them died due to COVID-19.

When it came to smoking status:

  • 59% had never smoked

  • 37% were ex-smokers

  • 3% were current smokers.

Current smokers were 80% more likely to be admitted to hospital and significantly more likely to die from COVID-19 than non-smokers.

Time to quit

Heavy smokers who smoked more than 20 cigarettes a day were 6.11 times more likely to die from COVID-19 than people who had never smoked.

The analysis also showed those with a genetic predisposition to being smokers had a 45% higher infection risk, and 60% higher hospitalisation risk.

The authors wrote: ‘Overall, the congruence of observational analyses indicating associations with recent smoking behaviours and [Mendelian randomisation] analyses indicating associations with lifelong predisposition to smoking and smoking heaviness support a causal effect of smoking on COVID-19 severity.’

In a linked podcast, Lead Researcher, Dr Ashley Clift, said: ‘Our results strongly suggest that smoking is related to your risk of getting severe COVID, and just as smoking affects your risk of heart disease, different cancers, and all those other conditions we know smoking is linked to, it appears that it’s the same for COVID. So now might be as good a time as any to quit cigarettes and quit smoking.’

These results contrast with previous studies that have suggested a protective effect of smoking against COVID-19. In a linked editorial, Dr Anthony Laverty and Dr Christopher Millet, Imperial College London, wrote: ‘The idea that tobacco smoking may protect against COVID-19 was always an improbable one.’

This article originally appeared on Medscape, part of the Medscape Professional Network. 


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