Observational data was analyzed alongside hospital coronavirus test data and UK Biobank genetic information for the first time, and the findings are 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 hospitalization for COVID-19, and 0.1% of them died because of COVID-19.
When it came to smoking status, 59% had never smoked, 37% were ex-smokers, and 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 nonsmokers.
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.
Analysis also showed those with a genetic predisposition to being smokers had a 45% higher infection risk, and 60% higher hospitalization risk.
The authors wrote: “Overall, the congruence of observational analyses indicating associations with recent smoking behaviors and [Mendelian randomization] 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, Anthony Laverty, PhD, and Christopher Millet, PhD, Imperial College London, wrote: “The idea that tobacco smoking may protect against COVID-19 was always an improbable one.”
A version of this article first appeared on Medscape.com.