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New Study Suggests Relationship Between Smoking and COVID-19 Severity

A large UK Biobank study published online in the respiratory journal Thorax, indicated that smoking may worsen the severity of the COVID-19 infection once contracted.

Diane Caruana

April 6, 2022

Findings keep suggesting that daily smokers have a significantly lower probability of developing symptomatic or a severe SARS-CoV-2 infection, when compared to the general population.

Findings related to the effect of smoking on COVID-19 patients have been inconsistent. To this effect, the study titled, “Smoking and COVID-19 outcomes: an observational and Mendelian randomisation study using the UK Biobank cohort,” combined observational and Mendelian randomization analyses with the aim of better understanding this relationship.

The research team analyzed 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, amongst 421,469 participants of the UK Biobank.

“There were 421 469 eligible participants, 1649 confirmed infections, 968 COVID-19-related hospitalisations and 444 COVID-19-related deaths. Compared with never-smokers, current smokers had higher risks of hospitalisation and mortality. In MR analyses of 281 105 White British participants, genetically predicted propensity to initiate smoking was associated with higher risks of infection and hospitalisation. Genetically predicted higher number of cigarettes smoked per day was associated with higher risks of all outcomes,” reported the researchers.

On analyzing this data, the research team concluded that smoking had a causal effect on risk of severe COVID-19. On the other hand, countless studies reported the opposite. Data from the Centers for Disease Control and Prevention (CDC) have shown that smokers represented just 1.3% of COVID-19 cases analyzed, while America’s adult smoking rate is at 13.7%. Similarly, a review of Chinese data published in the European Journal of Internal Medicine had reported that “active smoking does not apparently seem to be significantly associated with enhanced risk of progressing towards severe disease in COVID-19.”

The correlation between smoking and the susceptibility of contracting SARS-CoV-2

Another study conducted in a large French university hospital, between March and April 2020, aimed to determine the possible correlation of daily smoking, with the susceptibility of contracting the SARS-CoV-2 infection.

The researchers had estimated the rates of daily current smokers among COVID-19-infected patients and compared them to the rates of daily current smokers within the general French population, after controlling the data for sex and age.

The compiled data had indicated that the daily smokers’ rate amongst COVID-19 patients was at 5.3%, whilst within the general French population, the rate of daily smokers rate was of 25.4%. These findings had led the researchers to conclude that daily smokers have a significantly lower probability of developing symptomatic or a severe SARS-CoV-2 infection, when compared to the general population.