Nicotine patches are to be tested on coronavirus patients and healthcare workers treating infected people after initial studies suggested smokers were less likely to catch the disease.
Researchers in France say early data indicates those who smoke make up a disproportionately small number of people in hospital with COVID-19.
A study at Paris’s Pitie-Salpetriere hospital suggests a substance in tobacco, thought to be nicotine, was preventing smokers contracting coronavirus.
Those leading the study stressed they did not advise people to start smoking, with scientists pointing out it kills half of those who do so regularly – claiming around 75,000 deaths each year in France.
But they say they want to learn more after questioning 480 patients who tested positive for the virus. A total of 350 had to be treated in hospital while the rest with less serious symptoms were sent home.
Of those needing hospital treatment, whose median age was 65, just 4.4% were regular smokers. Only 5.3% of those allowed home – who had a median age of 44 – 5.3% reported they smoked.
The researchers said that according to the latest official statistics in France, smokers make up 30% of those aged 45-54, and 8.8% of women and 11.3% of men aged 65-75.
The authors write: “Our cross-sectional study strongly suggests that daily smokers have a much lower probability of developing symptomatic or severe SARS-CoV-2 infection compared to the general population.
“The effect is significant, it divides the risk by five for ambulatory patients and by four for hospitalised patients. You rarely see that in medicine.”
Eminent neurobiologist Jean-Pierre Changeux, who has reviewed the work, speculated that nicotine could protect against the virus by preventing it reaching the body’s cells.
It is also thought that nicotine could prevent the immune system going into overdrive due to the infection, as has been seen among some of the worst-affected cases.
Epidemiologist Florence Tubach, co-author of the study, cautioned: “Based on these results, however robust they may be, we must not conclude that there is a protective effect of tobacco smoke, which contains many toxic agents.
“Only nicotine or other modulators of the nicotinic receptor could have a protective effect and I maintain the conditional because our work remains observational.”
The next phase of the research will go ahead after the trials have been approved by France’s ministry of health.
Figures from hospitals in Paris show that of around 11,000 patients treat in hospital for COVID-19, 8.5% were smokers.
Official data indicates 25.4% of French people smoke.
It follows a study of more than 1,000 infected people in China, which found the proportion of smokers was 12.6% – compared to 28% across the country’s adult population.
