Are smokers more vulnerable to COVID-19? Here's what doctors say

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When, on March 21, Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization (WHO), took to Twitter to share general health guidelines to follow during the times of the novel coronavirus, he urged people to stop smoking as "it can increase the risk of developing severe disease, if one becomes infected with COVID-19".

Two days before that, the UK secretary of state for health, Matt Hancock, said in the House of Commons,"It is abundantly clear from the research into previous coronaviruses that smoking makes the impact of a coronavirus worse." At the same time in the US, the New York State Academy of Family Physicians (NYSAFP) announced that they are calling for a ban on the sale of all tobacco or vaping products during this pandemic period. The hashtag #QuitforCovid which calls on all smokers to give up on cigarettes has been gradually gaining traction across the world even as a number of publications come out with research that supports the hypothesis that smoking aggravates the impact of the coronavirus.

Dr Pankaj Chaturvedi, deputy director, Center For Cancer Epidemiology at Tata Memorial Center in Mumbai, who is also an anti-tobacco activist, quotes the findings of a study published in the Chinese Medical Journal which undertook research among patients affected by the coronavirus. "It found that those with a history of smoking were 14 times more likely to develop pneumonia than who did not smoke at all," he says. "Early evidence shows us that the ACE2 gene expression which the novel coronavirus uses to infect cells, is significantly higher in smokers than in non-smokers, thereby suggesting a higher susceptibility among smokers. Therefore, the entire cellular alteration that happens because of chronic smoking predisposes the body to infection and subsequent mortality."

The mode of transmission of the COVID-19 infection is through the respiratory epithelium which is the lining of our breathing tract, explain experts. This breathing tract is lined by a certain barrier called the ciliary epithelium which is known to get damaged in chronic smokers. "Now, when this immunological barrier is absent, the virus has a free entry into body's circulation leading to infection and subsequent damage," says Chaturvedi.

However, Dr Prashant Chhajed, head of department, respiratory medicine, at Fortis Hospital in Mumbai believes that it is wrong to say definitively that smokers are at an increased risk of getting the COVID-19 infection. "The COVID-19 is a new disease and so, we cannot say definitively that smokers have an increased risk of getting the infection. Of course, there is no denying the fact that smokers who have caught on to the virus will face more complications."

But experts agree that as WHO mentions, people who smoke are likely to touch their fingers to the lips and, therefore, the risk of transmission from the fingers to the mouth is high. Also, if a person already has a smoking-related disease such as the COPD (chronic obstructive pulmonary disease), then the chance of developing COVID-19 is also high.

"Also, the fact remains that smoking is an established risk factor for many respiratory infections such as influenza, as it reduces the immunological response which a person can otherwise surmount against any virus infection," says Chaturvedi. It causes a large amount of inflammatory changes leading to mucous formation that makes it difficult to clear the lungs. This, along with the immune-compromised state, leads to a greater risk of viral and bacterial infections.

Even though there is no real data to back up an association of vaping with increased COVID-19 rates, preliminary data shared by the CDC shows that young adults under the age of 44 years - the same population known for vaping - makes up a large part of the COVID-19 hospitalisation in the US. Dr Mukesh Goel, cardio thoracic surgeon, heart and lung transplant, Indraprastha Apollo hospitals, concurs with Chaturvedi: "The fact is that a person who smokes is always more susceptible to catching the COVID-19 infection because there is always a considerable damage and inflammation in the respiratory tracts of a chain smoker which makes them vulnerable to infections."

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