Smoking likely to worsen Covid severity, increase risk of death, UK study reveals

Compared to non-smokers, smokers are 80% more likely to contract severe Covid, study by Oxford university finds.

Representational image | Commons

New Delhi: Smoking is likely to worsen the severity of Covid and increase the risk of death from the virus, a first-of-its-kind study in the UK has revealed.

Published in the journal Thorax Monday, the study contradicts earlier assumptions and reports, which suggested smokers are less likely to suffer from severe Covid.

For the research, observational and genetic data from the UK on smoking and Covid was pooled to strengthen the evidence base by a team from the University of Oxford.

Data from primary care records, Covid-19 test results, hospital admissions data and death certificates of 4,21,469 participants were collected, to look for links between smoking and severity of Covid-19 infection from January to August 2020.

The data was collected from UK Biobank — a large, long-term study in the UK that is investigating the contributions of genetic predisposition and environmental exposure to the development of disease.

During the study period, 13,446 (3.2 per cent) people took a Covid-19 test and 1,649 (0.4 per cent) of them tested positive.

Of these, 968 (0.2 per cent) required admission to hospital and 444 (0.1 per cent) died as a result of their infection.

Smokers 80% more likely to get severe Covid

Over a third of the total 4,21,469 participants in the study — 37 per cent — were former smokers while 59 per cent had never smoked. Only 4 per cent were current smokers.

Of the current smokers, 71 per cent were light or moderate smokers who smoked 1 to 19 cigarettes a day. About 29 per cent were heavy smokers and smoked over 20 cigarettes a day.

According to the team’s analysis, compared to those who had never smoked, current smokers are 80 per cent more likely to be admitted and significantly more likely to die from Covid.

They also found that genetic predisposition (increased likelihood based on genetic makeup) to smoking was linked to a 45 per cent increased risk of infection and a 60 per cent higher risk of hospital admission for Covid-19.

Meanwhile, genetic predisposition to smoking heavily was linked to more than double the risk of infection, a five-fold increase in the risk of hospital admission and a 10-fold increase in the risk of death from the virus.

“The idea that tobacco smoking may protect against Covid-19 was always an improbable one,” wrote Anthony Laverty and Christopher Millet of Imperial College London, in an accompanying editorial.

“A respiratory pandemic should be the ideal moment to focus collective minds on tobacco control,” they added.

Earlier research on Covid and smoking

According to study researchers, existing scientific evidence on whether smoking is associated with a greater likelihood of more severe Covid infection has been inconsistent.

For example, a study from China, published in May 2020, found an unexpectedly low prevalence of smokers among Covid patients in the country.

Such studies also prompted clinical trials of nicotine therapy, based on the hypothesis that nicotine could stop the virus from propagating.

According to researchers at the University of Oxford, the existing research prompted them to get more clarity on the research between smoking and Covid to ensure accurate public messaging.