Covid-19 and smoking: the elephant in the room?

Kathryn Barnsley, Sukhwinder Singh Sohal

  • For more on COVID-19 and smoking, see the Tobacco Control resources page Click here

The role of smoking in the contraction, transmission and mortality rate of Covid-19 should be given research attention, and countries should allocate resources to health stimulus packages, scientific research, and actions to further reduce smoking rates. New research shows smoking has the potential to upregulate angiotensin-converting enzyme-2 (ACE2) receptor, which has been proved to be the receptor for both the SARS-coronavirus (SARS-CoV) and the human respiratory coronavirus NL638.

Liu et al found progression of Covid-19 was more likely to occur in smokers, and smokers were 14 times more likely than nonsmokers to progress to pneumonia. Reporting on Covid-19 hospitalized patients in China, Liu et al say:  “This study suggested that the progression group had a significantly higher proportion of patients with a history of smoking than the improvement/stabilization group.”

Cai recently reported higher ACE2 gene expression in smoker samples compared to never smokers. ACE2 is specifically expressed in a subset of type-2 alveolar cells (AT2), in which genes regulating viral reproduction and transmission are highly expressed. Smokers are therefore more susceptible to Covid-19 and smoking history should be considered in identifying the susceptible population and standardizing treatment regimens.

ACE2 could be a novel adhesion molecule for Covid-19 and potential therapeutic target for prevention of fatal microbial infections.  

Smokers contract more respiratory ailments, including colds, which also belong to the coronavirus family. Smokers are 34% more likely than non-smokers to contract  influenza,  and smoking is consistently associated with higher risk of hospital admissions after influenza infection.

Overall mortality is higher in older smokers, and smokers also have increased rates of bacterial pneumonia and tuberculosis. Further, many deaths from Covid-19 have been associated with underlying health conditions.

The damage caused to lungs by smoking makes patients more susceptible to pulmonary infections, both bacterial and viral.

Are COPD and other smoking related illnesses such as cardiovascular disease and diabetes masking reporting on smoking related Covid-19?

China has a high male smoking rate at around 50% in rural areas and is estimated to be about 44.8% overall. Most of the deaths identified from Covid-19 were in men in older age groups,

COPD is a smoking caused illness and is the fourth leading cause of death in the world.  Vaccination against influenza is strongly recommended for patients with COPD, because the frequency and progression of COPD exacerbations is strongly linked to respiratory viruses in 30% of cases.

We must bolster research, especially now, but also commit to the future as viruses will continue to emerge, especially zoonotic threats. “This is normal” says Professor Richt, a veterinary medicine researcher. Lum and Tambyah point out the medical system is built largely on commercial considerations; for example, when SARS (another coronavirus) emerged in November 2002, much effort was expended on vaccines and treatment, yet those funds disappeared as the epidemic subsided. “Scientists are now thawing old isolates from their freezers and rewriting grants, which…will be lost…when this epidemic inevitably comes to an end.”

The solid foundations of scientific research programs relating to emerging disease threats, which include laboratories, staff, equipment, and predictive modelling must be preserved so they can be built on at times of crisis. Not rebuilt every few years.

In coming months, WHO and countries should:

  • Ensure that the smoking status of patients identified with Covid-19 is recorded and included in all data sets, so that it can be determined if smokers are indeed more vulnerable.

Fund research into:

  • ACE2 as a novel adhesion molecule for Covid-19 and potential therapeutic target
  • If smokers, including young asymptomatic smokers, are more likely to transmit Covid-19 than non-smokers
  • Whether countries with high smoking rates are more vulnerable to Covid-19 than those with low smoking prevalence

Take decisive action to:

  • Provide COVID-19 context-specific advice to smokers to quit
  • Prioritise smokers as a vulnerable group, who should exercise caution and avoid areas where they may be liable to be exposed to Covid-19
  • Prioritize smokers for vaccination when a vaccine is developed
  • Fund and rapidly accelerate tobacco control actions, including taxation increases, minimum price policies, regulation of engineering and content of cigarettes, retail measures to reduce accessibility, enhanced cessation support and mass media anti-smoking campaigns.

Governments must take action to support strong scientific public health research systems, and to rapidly reduce smoking in all countries in accordance with the WHO Framework Convention on Tobacco Control (FCTC). This takes on new urgency in this time of global pandemic, as it appears highly probable that smoking exacerbates COVID-19 contraction, transmission and mortality.

Kathryn Barnsley is with the School of Medicine, University of Tasmania, Hobart, Australia. She has not declarations of support or conflicts of interest. She acknowledges advice from Anne Jones, The Union, (International Union against Tuberculosis and Lung Disease) for this article. Sukhwinder Singh Sohal is with the Respiratory Translational Research Group, Department of Laboratory Medicine in the School of Health Sciences, at the University of Tasmania, Launceston, Australia.  He is supported by Clifford Craig Foundation Launceston General Hospital.  Contacts: ;

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