Those who smoke are more likely to need hospital treatment and more likely to die from Covid-19 than non-smokers, new research shows.
Until now, experts said, there has been conflicting data on the extent to which smoking affects the risk of hospital admission from Covid-19.
But the study, led by Oxford University, is the first of its kind to look at both observational and genetic data on smoking and coronavirus.
To address the issue, the team looked at primary care records, Covid test results, hospital admissions data and death certificates.
421,469 people were included in the research and among them 1,649 tested positive for Covid, 968 were admitted to hospital related to the virus and 444 people died with Covid-19.
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The results showed that, compared with never-smokers, current smokers had an 80% higher risk of hospital admission with Covid-19.
They were twice as likely to die if they smoked one to nine cigarettes a day, while those smoking 10 to 19 cigarettes a day were almost six times more likely to die.
Among heavier smokers, people who smoked more than 20 a day, were over six times more likely to die compared to people who had never smoked.
Genetic analysis showed that among those genetically more likely to smoke, there was a higher risk of Covid infection and hospital admissions.
The authors concluded that their “results from two analytical approaches support a causal effect of smoking on risk of severe Covid-19”.
Dr Ashley Clift, the lead researcher from Oxford, 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.”