Smoking associated with increased risk of COVID-19 – Or maybe not?

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The government and the tobacco lobby are squaring up for another round of appeals and counter-appeals in the South African courts, over the state’s right to ban tobacco to as part of its anti-COVID-19 campaign. Both legal teams will be cherry-picking from research studies that have been confusingly contradictory in their findings, writes MedicalBrief.

That smoking is associated with an increased risk of COVID-19 symptoms and smokers are more likely to attend hospital than non-smokers, were the findings of a King’s College London study released this week. Simultaneously, a French study found the opposite – smokers had a lower risk than non-smokers of developing COVID-19.

Contradictions abound in this sub-field of coronavirus research – although the Kings College London researchers dismiss findings that contradict their conclusions as being the results of “biases in sampling, participation and response”. Dr Mario Falchi, lead researcher and senior lecturer at King’s, said that while some reports suggested a protective effect of smoking on COVID-19 risk: “Our results clearly show that smokers are at increased risk of suffering from a wider range of COVID-19 symptoms than non-smokers.”

Data from the US Centers for Disease Control and Prevention (CDC) have shown that smokers represented just 1.3% of COVID-19 cases analysed, while America’s adult smoking rate is at 13.7%, reports the industry publication Vaping Post. In response to these figures, the Norwegian Institute of Public Health removed smoking as a risk factor for severe coronavirus symptoms in April 2020. However, last September a genetic study from the Norwegian University of Science and Technology found a “clear and distinct” connection between smoking and developing a serious COVID-19 infection.

The French study, undertaken by universities and the military and just published in the journal Nicotine and Tobacco Research, found a “paradoxical link” between smoking and COVID-19 among 1,688 crew members who were exposed at the same time and same place to SARS-CoV2. The researchers found “a significant lower risk for developing COVID-19 in current smokers (71%) versus former and non-smokers (80%)”.

The abstract states: “This finding strongly supports the need for further research on nicotine physiological pathway and its impact on COVID-19 infection whilst emphasising that tobacco smoking should not be considered as an efficient protection against COVID-19.”

Also in the past week, a study from Hacettepe University and the Ankara Education and Research Hospital in Turkey looked at the effects of the pandemic on smoking addiction levels, and observed instances both of increases and decreases in addiction.

Two other studies have been widely publicised. One, 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 COVID.  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.

In the other study, anti-smoking researcher Dr Konstantinos Farsalinos and colleagues analysed data coming out of China, where it had been speculated that the higher hospitalisation and death rates among Chinese men was due to gender differences in smoking rates. However, Farsalinos fouind that there were significantly fewer smokers among hospitalised COVID-19 patients.

Similarly, another review of the Chinese data published in the European Journal of Internal Medicine concluded that “active smoking does not apparently seem to be significantly associated with enhanced risk of progressing towards severe disease in COVID-19”.

Last year, researchers from France’s Pasteur Institute and Sorbonne University found that the nicotinic acetylcholine receptor played a key role in the pathophysiology of COVID-19 infection. They wrote: “Nicotine may be suggested as a potential preventive agent against COVID-19 infection.”

However, there have also been numerous studies highlighting risks associated with smoking and COVID-19 infection and symptom severity, this week’s Kings College London study being among the most compelling.

Smoking associated with increased risk of COVID-19 symptoms

The Kings research, published in the BMJ journal Thorax, investigates the association between smoking and the severity of COVID-19. It found that smoking is associated with an increased risk of COVID-19 symptoms and smokers are more likely to attend hospital than non-smokers. This is the Kings College London material:

Researchers analysed data from the ZOE COVID Symptom Study App. Of the participants of the app, 11% were smokers. This is a lower proportion than the overall UK population of 14.7%, however, it reflects the demographics of the self-selected sample of the ZOE COVID Symptom Study.

While more than a third of users reported not feeling physically well during the period of study (24 March and 23 April 2020), current smokers were 14% more likely to develop the classic triad of symptoms suggesting diagnosis of COVID-19: fever, persistent cough and shortness of breath – compared to non-smokers.

Current smokers were also more likely to have a higher symptom burden than non-smokers. Smokers were 29% more likely to report more than five symptoms associated with COVID-19 and 50% more likely to report more than 10, including loss of smell, skipping meals, diarrhoea, fatigue, confusion or muscle pain. A greater number of symptoms suggested more severe COVID-19.

Additionally, current smokers who tested positive for SARS-CoV-2 were more than twice as likely as non-smokers to attend hospital.

The researchers recommended that a smoking cessation strategy be included as an element to address COVID-19, as smoking increased both the likelihood of symptomatic disease and disease severity. Reduction in smoking rates could also reduce the health system burden from other smoking-related conditions that require hospitalisation.

Dr Mario Falchi said: “Some reports have suggested a protective effect of smoking on COVID-19 risk. However, studies in this area can easily be affected by biases in sampling, participation and response. Our results clearly show that smokers are at increased risk of suffering from a wider range of COVID-19 symptoms than non-smokers.”

Claire Steves, lead researcher, consultant physician and reader at King’s College London, said: “As rates of COVID-19 continue to rise and the National Health Service edges towards capacity, it’s important to do all we can to reduce its effects and find ways to reduce hospital admissions.

“Our analysis shows that smoking increases a person’s likelihood to attend hospitals, so stopping smoking is one of the things we can do to reduce the health consequences of the disease.”

 

Study Details
Current smoking and COVID-19 risk: results from a population symptom app in over 2.4 million people

Nicholas S Hopkinson, Niccolo Rossi, Julia El-Sayed_Moustafa, Anthony A Laverty, Jennifer K Quint, Maxim Freidin, Alessia Visconti, Ben Murray, Marc Modat, Sebastien Ourselin, Kerrin Small, Richard Davies, Jonathan Wolf, Tim D Spector, Claire J Steves and Mario Falchi

Published in Thorax on 6 January 2021

 

Abstract

The association between current tobacco smoking, the risk of developing symptomatic COVID-19 and the severity of illness is an important information gap.

Methods
UK users of the Zoe COVID-19 Symptom Study app provided baseline data including demographics, anthropometrics, smoking status and medical conditions, and were asked to log their condition daily. Participants who reported that they did not feel physically normal were then asked by the app to complete a series of questions, including 14 potential COVID-19 symptoms and about hospital attendance.

The main study outcome was the development of ‘classic’ symptoms of COVID-19 during the pandemic defined as fever, new persistent cough and breathlessness and their association with current smoking. The number of concurrent COVID-19 symptoms was used as a proxy for severity and the pattern of association between symptoms was also compared between smokers and non-smokers.

Results
Between 24 March 2020 and 23 April 2020, data were available on 2,401,982 participants, mean (SD) age 43.6 (15.1) years, 63.3% female, overall smoking prevalence 11.0%. 834,437 (35%) participants reported being unwell and entered one or more symptoms.

Current smokers were more likely to report symptoms suggesting a diagnosis of COVID-19; classic symptoms adjusted OR (95% CI) 1.14 (1.10 to 1.18); >5 symptoms 1.29 (1.26 to 1.31); >10 symptoms 1.50 (1.42 to 1.58). The pattern of association between reported symptoms did not vary between smokers and non-smokers.

Interpretation
These data are consistent with people who smoke being at an increased risk of developing symptomatic COVID-19.

 

French study details

Impact of Tobacco Smoking on the risk of COVID-19. A large scale retrospective cohort study

Nicolas Paleiron, Aurélie Mayet, Vanessa Marbac, Anne Perisse, Hélène Barazzutti, François-Xavier Brocq, Frédéric Janvier, Dautzenberg Bertrand and Olivier Bylicki.

The authors are affiliated to these institutions in Toulon, France: Respiratory Disease Unit, HIA Sainte-Anne, the 9th Military Medical Center, the Aeromedical Military Center, and the Biology Unit at HIA Sainte-Anne. Other affiliations are the APHP Sorbonne University in Paris, and in Marseille French Military Center for Epidemiology and Public Health (CESPA) and UMR 912 SESSTIM: INSERM-IRD-Université Aix-Marseille.

Published in the journal Nicotine and Tobacco Research on 9 January 2021.

 

Abstract

Preliminary reports indicated that smokers could be less susceptible to the coronavirus SARS-CoV-2, which causes COVID-19. However, once infected an increased risk of severe disease is reported. We investigated the association between smoking and COVID-19 during an outbreak of the disease on a naval vessel.

Methods

We conducted a cross-sectional, observational study on the 1,769 sailors of a same navy aircraft carrier at sea exposed at the same time to SARS-CoV2 to investigate the link between tobacco consumption and COVID-19.

Results

Among the 1,688 crew members (87% men; median age= 28 (IQR 23-35)) included, 1,279 (76%) developed COVID-19 (1038 (62%) RT-PCR-positive and 241 (14%) with only clinical signs). One hundred and seven patients were hospitalised.

The univariable analysis odds ratio (OR) for COVID-19 infection was 0.59 (95% confidence interval (CI), 0.45-0.78; P<0.001) for current smokers vs. former and nonsmokers; sex, body mass index or blood group had no significant impact. Crewmembers >50 years old had an increased risk of contracting COVID-19 (OR, 2.84 [95% CI, 1.30-7.5]; P=0.01).

Multivariable analysis retained the lower risk of current smokers becoming infected (OR, 0.64 [0.49-0.84]; P<0.001) and age >50 years was significantly associated with COVID-19 (OR, 2.6 [1.17-6.9]; P=0.03).

Conclusions

Current smoking status was associated with a lower risk of developing COVID-19 but cannot be considered as an efficient protection against infection. Mechanism of the lower susceptibility of smokers to SARS-CoV-2 requires further research.

Implications

Recent epidemiologic data suggest a paradoxical link between smoking and COVID-19. Among the 1,688 crewmembers (with an attack rate of 76% and exposed at the same time in the same place to SARS-CoV2), we found a significant lower risk for developing COVID-19 in current smokers (71%) versus former and non-smokers (80%).

This finding strongly supports the need for further research on nicotine physiological pathway and its impact on COVID-19 infection whilst emphasizing that tobacco smoking should not be considered as an efficient protection against COVID-19.

 

Study details

Evaluation of the Effect of the COVID‐19 Pandemic on Smoking Addiction Levels

Izzet Fidanci, Hilal Aksoy, Duygu Yengil Taci, Duygu Ayhan Baser and Mustafa Cankurtaran

The authors are in the Faculty of Medicine at Hacettepe University and the Ankara Education and Research Hospital in Ankara, Turkey.

The International Journal of Clinical Practice, first published on 7 January 2021.

 

Abstract

This study aims to evaluate the changes in smoking addiction levels during the ongoing COVID‐19 pandemic.

Methods

This study included 104 participants ≥18 years old who were previous patients of family health clinics for a variety of reasons in the months preceding the onset of the COVID‐19 pandemic. The Fagerström Test for Nicotine Dependence was administered to these patients as part of their initial intakes.

The participants were asked to complete a questionnaire related to socio‐demographic information and the Fagerström Test for Nicotine Dependence after obtaining agreement to participate during the pandemic period. In addition, written informed consent was obtained. The Statistical Package for the Social Sciences, version 20, was used to analyse the acquired data.

Results

The participants were 48.1% and 51.9% females and males, respectively. The pre‐pandemic and COVID‐19 pandemic mean smoking addiction scores were 5.03 and 5.6, respectively.

The smoking addiction levels before and during the COVID‐19 pandemic significantly differed (p < 0.001).

Of the individuals with low smoking addiction levels before the pandemic, 17.6% and 29.4% became moderately and highly addicted, respectively. Of the individuals with moderate smoking addiction level, 6.3% and 43.9% became lowly and highly addicted, respectively.

Conclusion

The smoking addiction level may change based on various factors including behavioural changes. While increases in smoking addiction during the pandemic can be observed due to behavioural changes and anxieties that may arise due to the pandemic, a decrease in addiction levels and even smoking cessation can also be observed during these times due to the more progressive course of COVID‐19 in smokers.

Health institutions should therefore take advantage of this period and focus more efforts on the cessation of smoking and other substance abuse issues.

 

A nicotinic hypothesis for COVID-19 with preventive and therapeutic implications

Jean-Pierre Changeux, Zahir Amoura, Felix A Reyd and Makoto Miyarab

Pasteur Institute, Sorbonne University and Assistance Publique-Hôpitaux de Paris.

Published in Comptes Rendus. Biologies, Volume 343, Issue 1 (2020). Accepted in April and published on 5 June 2020.

 

Abstract

The SARS-CoV-2 epidemic raises a considerable issue of public health at the global scale. There is a pressing urgency to find treatments based upon currently available scientific knowledge. Therefore, we tentatively propose a hypothesis which hopefully might ultimately help save lives.

Based on the current scientific literature and on new epidemiological data which reveal that current smoking status appears to be a protective factor against the infection by SARS-CoV-2 [1], we hypothesise that the nicotinic acetylcholine receptor (nAChR) plays a key role in the pathophysiology of COVID-19 infection and might represent a target for the prevention and control of COVID-19 infection.

 

Kings College London material – Smoking associated with increased risk of COVID-19 symptoms (open access)

 

Thorax study (Open access)

 

Impact of Tobacco Smoking on the risk of COVID-19. A large scale retrospective cohort study (Open access)

 

Vaping Post – Another French Study Looks Into The Use of Nicotine Against COVID-19 (open access)

 

The International Journal of Clinical Practice – Evaluation of the Effect of the COVID‐19 Pandemic on Smoking Addiction Levels (open access)

 

Comptes Rendus. Biologies article: A nicotinic hypothesis for COVID-19 with preventive and therapeutic implications

 

See also from the MedicalBrief Archives:

Nicotine patches study awaits approval after French study finds nicotine may be a COVID-19 preventative

 


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