Tobacco kills more than eight million people globally every year. Over seven million of these deaths are directly associated with tobacco use whereas around 1.2 million non-smokers die after being exposed to second-hand smoke. High taxes on tobacco products are a major source of revenue for governments but at the same time, there is heavy public health expenditure on tobacco-related diseases, many of which are actually preventable.
Tobacco is consumed in different forms like, tobacco chewing, paan masala, bidi, cigarette smoking, hookah and this has large geographical variations.
The coronavirus pandemic has again sparked a discussion on tobacco use and the associated risks of respiratory infections. It is well established that tobacco smoking can lead to a variety of diseases of the cardiovascular system, central nervous system and respiratory system. It is also a major risk factor for many cancer types, primarily lung cancer. Apart from being a known risk factor, tobacco smoking has been associated with an increase in severity of respiratory diseases.
Smoking is associated with an increased incidence of Acute Respiratory Distress Syndrome (ARDS) in people with a risk factor like severe infection, non-pulmonary sepsis (blood infection), or blunt trauma. People who have any cotinine — a metabolite of nicotine associated with second-hand smoke — in their body, even at the low levels, are at an increased risk of developing acute respiratory failure from ARDS. The World Health Organization (WHO) has stated that smokers are more vulnerable to COVID-19 and the chances of them contracting severe diseases are more if they acquire the infection as compared to non-smokers.
WHO has suggested the reduction of tobacco use as this may be harmful to COVID-19 patients. This has been advocated widely to minimise the suffering of the global population. There have been multiple theories, both in favour and against, on the effects of tobacco consumption on COVID-19 patients.
A study of University College, United Kingdom found that current smokers were 1.45 times more likely to have severe complications compared to former and non-smokers while looking for the prevalence of smoking as well as COPD (chronic obstructive pulmonary disease) in COVID-19 patients. Critically ill COVID-19 patients with COPD had a 63% risk of severe disease and a 60% risk of mortality, while critically ill patients without COPD had only a 33.4% risk of severe disease and a 55% risk of mortality.
In a Chinese study, 25.5% of the 1,099 COVID-19 patients admitted to ICU were smokers. In another COVID-19 data of the US population, over 8% patients admitted to ICU and 6% hospitalised patients were either current or former smokers. Many studies from China, South Korea, and US found that smoking is associated with increased risk of acquiring severe coronavirus infection, needing ICU admissions and mechanical ventilation or death.
Researchers believe that smokers are more prone to acquiring respiratory symptoms due to the absence of cilia in their airway. Cilia are tiny hair-like structures present in the airway lining and help to keep the airway clean by removing the mucous and infectious agents. Cilia are destroyed by inhaled chemicals of cigarettes over the period of time. Smoking is associated with increased expression of Angiotensin-converting enzyme II (ACE-2) gene.
Some reports suggest that smokers are more vulnerable to COVID-19, as their fingers are frequently in contact with their lips, increasing the likelihood of the virus being transmitted from their hands. Smokers have compromised lung function with reduced breathing capacity, which could impact their ability to fight the coronavirus disease. A study from China reported a higher incidence of severe pneumonia in smokers with COVID-19 whereas more number of COVID-19 death in smokers were correlated with poor lung health due to tobacco use.
One news article which made claims about the protective effect of smoking for COVID-19 along with two scientific reports suggesting that smoking and nicotine may be protective against COVID-19. The number of COVID-19 patients among smokers were far less than in the general French population. The University of Bath rejected this claim by quoting one of the authors longstanding association to the tobacco industry and lack of information regarding source of funding and potential conflict of interests.
The World Health Organization (WHO) issued a statement underlining the perils of smoking, and referring to “unproven claims that tobacco or nicotine could reduce the risk of COVID-19”. This came days after researchers published a hypothesis that nicotine may be protective in novel coronavirus SARS-CoV-2.
COVID-19 is an infectious disease that primarily attacks the lungs. Smoking impairs lung function making it difficult for the body to fight off coronaviruses and other diseases. Tobacco is also a major risk factor for non-communicable diseases like cardiovascular disease, cancer, respiratory disease and diabetes and COVID associated illnesses are more severe or critical in patients with comorbidities.
WHO is constantly evaluating new research, including research that examines the link between tobacco use, nicotine use, and COVID-19. WHO urges researchers, scientists and the media to be cautious about amplifying unproven claims that tobacco or nicotine could reduce the risk of COVID-19.
It is recommended that one take immediate steps to quit by using proven methods such as toll-free quit-lines, mobile text-messaging programmes, and nicotine replacement therapies. WHO stresses the importance of ethically approved, high-quality, systematic research that will contribute to advancing individual and public health, emphasising that the promotion of unproven interventions could have a negative effect on health.
Even if a person is not affected by coronavirus infection, it is a good time to stop smoking. This improves immunity and can improve lung function within a few months. Quitting, even after smoking-related problems have developed, will likely improve life expectancy and bring both immediate and long-term health benefits. Within 20 minutes of quitting, elevated heart rate and blood pressure drop. After 12 hours, the carbon monoxide level in the bloodstream drops to normal. Within 2-12 weeks, circulation improves and lung function increases. After 1-9 months, coughing and shortness of breath decrease.
Much of the global focus on tobacco prevention and cessation focuses around non-infective respiratory, cardiovascular, and cancer-related deaths. The risk of infectious complications is, however, the predominant focus and of utmost concern in low-income and middle-income countries, particularly during a pandemic. India has banned the sale of tobacco products during lockdown periods. Over 25 states and union territories, including Maharashtra, Gujarat, Uttar Pradesh, Assam and Delhi, have banned the use of smokeless tobacco products and spitting in public places in view of COVID-19. Although there is a paucity of data on tobacco ban in this crisis and its potential benefit in COVID-19, current smokers are advised to stop smoking in this pandemic and beyond.
The world should aim to be tobacco-free, but given the intricate web of finance, taxes, jobs, lobbying, and politics, this is unlikely to happen in the near future. However, the battle against tobacco use should continue, by assisting smokers to successfully and permanently quit. Avoiding COVID-19 now, but having lung cancer or COPD later on, is not a desired outcome; therefore, any short-term interventions need to have long-term sustainability.
(With inputs from Deepak Saini and Rakesh Yadav).
(Dr Abhishek Shankar is Assistant Professor in Radiation Oncology at Lady Hardinge Medical College & SSK Hospital, Delhi. Dr Deepak Saini is Project Officer at Cancer Control and Prevention Division of Indian Society of Clinical Oncology, Delhi. Dr Rakesh Yadav is Professor in the Department of Cardiology at All India Institute of Medical Sciences, Delhi. Views expressed are personal.)