Smokers 80 per cent more likely to be hospitalised with COVID-19

Stark findings highlight increased health risk smokers face from COVID-19.

Current smokers are 80 per cent more likely to be admitted to hospital and significantly more likely to die from COVID-19 compared with those who have never smoked, new research has revealed.

The study led by researchers from Oxford University in the UK, analysed data from primary care records, COVID-19 test results, hospital admissions data and death certificates to look for associations between smoking and COVID-19 infection severity from January to August 2020 in 421,469 participants of the UK Biobank, all of whom had had their genetic make-up analysed when they agreed to take part in 2006-10. 

This was the first study of its kind to examine observational and genetic data on smoking and COVID-19.

During the study period, 13,446 people took a COVID-19 swab (PCR) test, 1,649 of whom tested positive; 968 required admission to hospital; and 444 died as a result of their infection. 

The majority of those involved in the study or 59 per cent had never smoked; over a third (37%) were former smokers; and only 4 per cent were current smokers. Among current smokers, most (71%) were light or moderate smokers (1-19 cigarettes/day); only 29 per cent were heavy smokers (20+/day).

Compared with those who had never smoked, current smokers were 80% more likely to be admitted to hospital and significantly more likely to die from COVID-19.

The researchers also assessed whether a genetic predisposition to smoking and heavy smoking might have a role in COVID-19 severity among 281,105 of the original participants living in England. 

This revealed that a genetic predisposition to smoking was associated with a 45 per cent higher risk of infection and a 60 per cent higher risk of hospital admission for COVID-19. 

It also revealed that a genetic predisposition to smoke more heavily was associated with a more than doubling in the risk of infection; a 5-fold increase in the risk of hospital admission; and a 10-fold increase in the risk of death from the virus.

While the researchers acknowledged that they relied only on hospital COVID-19 test data rather than on more representative community data, they nevertheless point to the similarity of the findings in both sets of analyses. 

Commenting Norma Cronin, chairperson of ASH Ireland, Council of the Irish Heart Foundation said, “The stark findings of this latest piece of research highlights the increased health risk that smokers face from the dangers of COVID-19. We would always encourage smokers to quit for the enormous health benefits, but particularly now with COVID-19 still live in our communities, we would implore those smoking to avail of all HSE quit supports and kick the habit once and for all.

“The COVID-19 pandemic has been tragic for all of us so we are deeply concerned for the health and safety of the hundreds of thousands of smokers in Ireland as this research suggests that they are up to 80 per cent more likely to be admitted to hospital with Coronavirus. Countless lives have been lost tragically to Covid-19, so in light of this research, we would urge smokers to quit once and for all.’’

In a linked podcast, lead researcher Dr Ashley Clift had a clear message for smokers. 

“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.”

Support is available to stop smoking is Ireland’s dedicated smoking cessation service and smokers can give themselves the best chance of stopping by following the plan, which sees thousands of people successfully give up each year.

The HSE QUIT service provides personalised, free support by phone, email, SMS and live chat. Smokers can free call 1800 201 203 or visit for stop smoking tips and resources, a free QUIT Kit, and to create a QUIT Plan. Peer-to-peer support is available on the QUIT Facebook Page or on Twitter at HSE QUIT @HSEQuitTeam  #TheLastStop #QuitandWin.

(Smoking and COVID-19 outcomes: an observational and Mendelian randomisation study using the UK Biobank cohort doi:10.1136/thoraxjnl-2021-217080)