Given that tobacco use is thought to kill an estimated eight million people every year, a recent report that claimed that smokers were less likely to contract coronavirus raised eyebrows.
The preliminary study, by the Pitié-Salpêtrière Hospital in Paris, stated that "current smoking status appears to be a protective factor against the infection by SARS-CoV-2".
Pitié-Salpêtrière Hospital wrote that "nicotine may be suggested as a potential preventive agent against COVID-19 infection", based on scientific literature and the hospital's own observations.
But the study also warned that "nicotine is a drug of abuse responsible for smoking addiction".
"Smoking has severe pathological consequences and remains a serious danger for health".
Despite this, the new information has clouded evidence about the relationship between smoking and COVID-19, the disease caused by the novel coronavirus.
So what do world health experts say? Are smokers less likely to contract the virus?
No. According to the World Health Organization (WHO), those who smoke are likely to be more vulnerable to infection.
"Smokers may also already have lung disease or reduced lung capacity which would greatly increase the risk of serious illness."
"Conditions that increase oxygen needs or reduce the ability of the body to use it properly will put patients at higher risk of serious lung conditions such as pneumonia."
Studies also show that smokers were more likely to die than non-smokers during the Middle Eastern Respiratory Syndrome (MERS) outbreak in 2012.
“People who smoke have poorer lung health, so you’re already starting at a poorer baseline," said Dr Sara Kayat, a UK GP.
"We also know that people who smoke have an increased risk of other kinds of issues, like COPD, an underlying chronic lung disease, heart attacks and strokes."
Higher risk of severe outcomes from COVID-19
It is also theorised that smokers are more at risk of infection because of the effect tobacco can have on ACE2 (angiotensin-converting enzyme II) receptors. These gene expressions are located in human cells, and notably in the respiratory system.
"COVID-19 needs to sit in this receptor to spread and duplicate, and we also know that smoking can up-regulate this receptor, so it can create more of these receptors for COVID-19 to sit within," Dr Kayat told Euronews.
"It may be that this is how smoking might contribute to a higher risk of serious consequences."
A report in March by the European Centre for Disease Control (ECDC) has also identified smokers as a "vulnerable group" to infection from COVID-19, due to the "higher susceptibility" of ACE2 receptors.
Meanwhile, the World Health Organization have also suggested that the very act of smoking increases the possibility of virus transmission.
"Fingers are in contact with lips ... and smoking products such as water pipes often involve the sharing of mouthpieces and hoses, which could facilitate the transmission of COVID-19 in communal and social settings."
But while smoking does has a number of negative connotations, there is little evidence to supplement this theory.
"There may be higher risks of severe outcomes from COVID-19, but whether or not smokers are more likely to catch COVID-19 is still up for debate," Dr Kayat told Euronews.
"I would not suggest using smoking as a way of preventing getting coronavirus, and certainly cutting back on your use of tobacco may help".
Speaking to Euronews, the World Health Organization say they are currently reviewing research and studies concerning smoking and nicotine and will release further statements in the coming days.
"The current evidence suggests that the severity of COVID is higher among smokers," it said.
"The only people who should be using nicotine patches right now are people who need to use them to quit smoking."
Health risks linked to excessive consumption or misuse
The advice from the World Health Organization has also been echoed by national authorities across Europe.
A local Foundation Trust for the UK's National Health System has released information about the coronavirus that there is "an increased risk for people who smoke".
“If you are going to give up smoking, this is a very good moment to do it,” said Chief Medical Officer, Prof. Chris Whitty.
NHS guidelines also state that smoking increases the risk of "more than 50 serious health conditions".
The French Health Ministry has stated that smokers are not more of risk of contamination, but they are "more at risk of developing serious conditions".
France has severely curtailed the sale of nicotine products after the recent study in Paris.
Pharmacies are now limited to selling no more than one-month supplies of any nicotine products aimed at curbing dependence on cigarettes.
Meanwhile, the online sale of products has been banned altogether.
The Health Ministry said the measures were taken to "prevent the health risk linked to the excessive consumption or misuse" of nicotine products by people hoping to protect themselves from COVID-19.
The Pitié-Salpêtrière hospital in Paris is planning to clinically test the use of nicotine patches on hospitalised COVID-19 patients to investigate their theory.
Researchers are nevertheless not encouraging citizens to take up smoking, due to other potentially fatal health risks that are involved.