PARIS France (El Mundo) – Why are there so few smokers among coronavirus patients? Does nicotine stop the virus from spreading? A group of French scientists will try to answer the second question. Because, surprisingly, one study shows that the percentage of smokers among patients is notoriously below average. There is a hypothesis that would explain this, developed by an eminent neurobiologist. To corroborate the hypothesis, three clinical trials with nicotine patches will be carried out.
As in the cigarette packets, before you read on, the warning. The words of the French Minister for Health, Olivier Vérin: “Be careful, this does not mean that tobacco protects. Tobacco causes more than 70,000 deaths a year. It means that there is an interesting clue, among others, that seeks to understand why the biochemical mechanism of nicotine could be a marker of resistance to this epidemic”.
It all started with the intuition of a resident.
“One of my students, Dr. Makoto Miyara, drew my attention in mid-March to the low smoking rate among Chinese hospital patients,” says Professor Zahir Amoura, head of the internal medicine service 2, autoimmune and systemic diseases at La Pitié Salpêtrière Hospital in Paris, a public center linked to Sorbonne University.
The chief admits in Le Figaro that he was skeptical and found it extravagant that a lung infection would elude smokers. But the intern insisted… Both sign, along with two prominent members of the Pasteur Institute, Nicotine Hypothesis for Covid-19 with preventive and therapeutic implications, published this week by the Academy of Sciences, available on the Qeios site.
The data. Of the 343 patients hospitalized in his health center, with an average age of 65 years, only 4.4% were regular smokers. And among the 139 who have gone to consultation, average age 44 years, only 5.3% had the vice. According to the latest French Public Health barometer, 30% of French people between 45 and 54 are smokers. In the 65-75 age group, 8.8% of women and 11.3% of men smoke.
“It is very rare to observe such a protective factor in epidemiology,” said the head of the La Pitié public health department, Florence Tubach, who decided to carry out the study to corroborate the initial intuition.
Other data from the Assistance Publique-Hôpitaux de Paris confirm this significant difference. Of the 11,000 patients hospitalized by Covid-19 since the beginning of the epidemic until the beginning of April, only 8.5% were regular smokers. This is in startling contrast to 25.4% of French people who are addicted to tobacco.
A Chinese study published at the end of March in the New England Journal of Medicine, on more than a thousand people infected with the disease showed that 12.6% smoked, much lower than the percentage of smokers in China (28%).
We put the figures aside because of Jean Pierre Changeux, eminent neurobiologist, honorary professor at the Collège de France and the Pasteur Institute, a member of the Academy of Sciences for three decades and, famous for having identified the nicotinic acetylcholine receptor.
He had been struck by the fact that some infected people lose their sense of smell. That reminds him of other viruses like the flu or polio. “The coronavirus could be a neurotrophic virus that spreads, at least partially, through the nervous system from the epithelium to the olfactory bulb, then to the brain stem and on to the respiratory centers.”
In statements to Le Figaro, the biologist tells how he thought of the rabies virus entering the nervous system through the nicotine receptors and moving up the spinal cord. “If you look at the genetic sequence of the rabies virus envelope, you can see a very curious element, close to the structure of the snake’s venom”: These envelope proteins have a ‘finger’ that allows them to hook onto the nicotine receptor and open the door to penetrate the cell.
Changeux asked a colleague at the Pasteur Institute, Felix Rey, for the coronavirus sequence. And there were the little dots that cover its surface, “which reminds us of the ‘fingers’ that can link up with the nicotine receptor,” the biologist explained.
At the time, Changeux was not aware of the study on smoking. Smokers are presented as an at-risk population, especially since their condition degrades faster than that of other hospitalized patients.
Randomness.
The prestigious researcher talks to Serge Haroche, winner of the 2012 Nobel Prize for Physics, who tells him that his son is a doctor at La Pitié and that his colleagues are wondering about the protective effect of tobacco. And he contacts the doctors. “The hypothesis is that nicotine, by fixing itself on the cell receptor used by the coronavirus, prevents it from doing so and then penetrating the cells and spreading,” he explains to Agence France Presse. In two words, the nicotine from smokers closes the door to the cells for the virus because it was there before.
Another less privileged hypothesis is that nicotine would also reduce the excessive immune response that occurs in the most severe cases.
Hypotheses have to be tested.
Three trials with nicotine patches are going to be conducted as soon as the groups are organized, and non-nicotine patches are made that will play the role of the placebo effect.
The first group is looking at 1500 people. The other two will have 200 hospitalized patients and another 200 patients in resuscitation. The aim is to see if nicotine cures the most serious and prevents others from developing a severe form of the disease.
“We are going to work with an accelerated schedule, but we must be prudent and rigorous,” says Zahir Amoura. “We are going to give nicotine to people who don’t smoke. We are moving into unknown territory, full of uncertainties, notoriously in terms of dosage”.
Doctors involved, including minister Olivier Véran who is a neurologist and was a consultant in Grenoble as a member of parliament before being appointed minister in February, warn against any temptation to go to the pharmacy for patches or to the store for cigarettes. One is dangerous, and the other… is bad.
