Smokers face higher infection risk

KUALA LUMPUR: Smokers have a higher risk of contracting and dying from Covid-19, data has suggested.

Lung specialists said that emerging published data from China recently has suggested that smokers may have a greater risk of contracting and dying from Covid-19 while raising a concern they could pose a greater risk of spreading the respiratory disease.

Quoting a recently published New England Journal of Medicine study of 1,099 Covid-19 patients in China, cardiothoracic surgeon and Lung Cancer Network Malaysia (LCNM) president Dr Anand Sachithanandan said 17 out of 137 current smokers (12.4%) required admission in the intensive care unit (ICU), mechanical ventilation or died while only 44 out of 927 non-smokers (4.7%) were in those categories.

“This was an observational study, hence it is difficult to adjust for possible confounding risk factors but it suggests smokers are more likely to develop severe disease that requires admission to ICU, mechanical ventilation or results in death, compared to non-smokers, ” he said in an interview.

The virus which predominantly affects the respiratory system requires a living host to survive and replicate, causing severe illness, he explained.

Dr Sachithanandan said the critical entry point for the novel coronavirus SARS-CoV-2 to infiltrate and subsequently bind to human cells (the host) was through the angiotensin-converting enzyme-2 (ACE-2) receptor located mainly in the lungs (type II pneumocytes) and the lining (epithelium) of the airways.

(Other receptor sites are kidneys, small intestine and the lining of blood vessels or endothelium.)

ACE-2 is part of a hormone system that regulates blood pressure and fluid/salt balance in the body.

“Scientists have identified that tobacco smoking and possibly even e-cigarettes can increase expression of these ACE-2 receptors, thereby enabling greater viral entry, reproduction and transmission.

“This is a plausible scientific reason why smokers may be more susceptible to a more severe Covid-19 illness due to the greater viral load.

“Quitting smoking during these anxious times may be difficult but the health and economic benefits are immense, ” said Dr Sachithanandan, adding that this will significantly cut the risk of developing lung cancer too.

LCNM co-founder, clinical oncologist Dr Tho Lye Mun, emphasised that quitting smoking was socially responsible and might help mitigate a spike in Covid-19 cases as much as proper hand washing or social distancing.

Besides contact between hands and lips and possible environmental contamination of cigarette or device, the exhaled breath of an infected (but asymptomatic) smoker may exacerbate viral spread through aerosolisation, he noted.

“Health authorities should collect data on the smoking status of all Covid-19-positive cases and deaths.

“That’s because smoking prevalence remains high among adult Malaysian males, at around 45%, ” he said.

Both doctors stressed the importance of robust data collection and rigorous analysis in unlocking the potential of drugs targeting the ACE-2 receptor to successfully treat Covid-19 until an effective vaccine becomes widely available.

Universiti Malaya’s Nicotine Addiction Research and Collaborating Centre head Dr Amer Siddiq Amer Nordin said vaping, more than smoking cigarettes, was aerosolised and this raised the concern over whether vapers could spread Covid-19.

Following information from China, the World Health Organisation has also warned that people who have cardiovascular and respiratory conditions caused by tobacco use, or otherwise, are at higher risk of developing severe Covid-19 symptoms.

It also said waterpipe communal use and sharing of the mouthpiece and hose increased the potential for the transmission of infectious diseases between users.