The results appear to tally with another study by the Pitié-Salpêtrière Hospital in Paris, which questioned 480 patients who tested positive for the virus.
According to their findings, among the 350 patients hospitalised, whose median age was 65, only 4.4 per cent were regular smokers. Among those released home, with a median age of 44, 5.3 per cent smoked.
The French health authority Santé Publique France puts the number of smokers in the general population at 32 per cent of people between 18 to 75 years old.
“Compared to the French general population, the Covid-19 population exhibited a significantly weaker current daily smoker rate by 80.3 per cent for outpatients and by 75.4 per cent for inpatients,” the researchers wrote in their study.
“Thus, current smoking status appears to be a protective factor against the infection by SARS-CoV-2.”
The researchers said that a “nicotinic acetylcholine receptor (nAChR)” plays a key role in infection from the coronavirus and that nicotine may act to protect this receptor from attack. It may also lessen the overreaction of the body’s immune system that has been found in the most severe cases of Covid-19 infection.
Clinical trials of nicotine patches on health workers and patients are awaiting the approval of the country’s health authorities.
Health minister Olivier Véran called the study "interesting", adding: "We will not be shutting any doors and certainly not that one."
Smoking causes 75,000 deaths in France and researchers were at pains to point out that nobody should take up the habit as a preventative measure.
“One should not forget that nicotine is a drug of abuse responsible for smoking addiction," they wrote.
“Smoking has severe pathological consequences and remains a serious danger for health. Yet under controlled settings, nicotinic agents could provide an efficient treatment for an acute infection such as Covid-19,” they concluded.