People who smoke ‘significantly more likely to die’ from COVID

The study, published in Thorax and said to be the first of its kind, combined observational and Mendelian randomisation analyses. Looking at medical data and COVID test results in the UK, researchers examined genetic data for close to 300,000 people.
 
Researchers found that a genetic predisposition to smoking is associated with a 45% higher risk of COVID infection and a 60% higher risk of hospitalisation.
 
They also found a genetic predisposition to smoking more heavily is associated with more than double the risk of infection, a five-fold increase in the risk of hospitalisation, and a 10-fold increase in the risk of death from COVID.
 
Most study participants (59%) had never smoked, 37% had formerly smoked, and only 4% were current smokers. Among the people who currently smoke, 71% were light or moderate smokers (1–19 cigarettes a day), and 29% smoked heavily (20 or more a day).
 
Compared with those who had never smoked, people who currently smoke are 80% more likely to be admitted to hospital and significantly more likely to die from COVID-19.
 
‘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,’ they said.
 
Mendelian randomisation uses genetic variants as proxies for a particular risk factor – in this case, genetic variants that make someone more likely to smoke or smoke more heavily – to obtain genetic evidence in support of a causal relationship.
 
According to the researchers, existing evidence on whether smoking is associated with more severe COVID infection has been inconsistent. Most of the research to date has been observational and unable to establish a causal effect.
 
‘Several studies carried out early on in the pandemic reported a lower prevalence of active smokers among people admitted to hospital with COVID-19 than in the general population. But other population-based studies have suggested that smoking is a risk factor for the infection,’ they stated.
 
Speaking in an associated podcast, researcher Dr Ashley Clift said the new study delivers a clear message for people who smoke.
 
‘Our results strongly suggest that smoking is related to your risk of getting severe COVID,’ he said.
 
‘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.’
 
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hospitalisation severe COVID smoking