Could Covid be treated with nicotine? French researchers are trying to find out
In the first few months of the Covid pandemic, doctors treating patients around the world noticed that there were fewer smokers among their most serious cases. Some suggested the nicotine in cigarettes could be slowing down the virus. A hospital in Paris is putting this hypothesis to the test, leading studies using nicotine patches.
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It all started with clinical observations that the proportion of smokers in hospitalised Covid patients appeared to be less than the general population.
"This has been observed, and it is accepted as an epidemiological fact, that when you take patient populations with Covid, the proportion of smokers is significantly lower than in the general population,” said Zahir Amoura, a doctor at the Pitié-Salpétrière hospital in Paris, told RFI.
"Of course, that does not mean we think people should start smoking to protect themselves from Covid,” he insisted. “Smoking is a scourge. It’s important to repeat that.”
Smokers’ paradox
The so-called ‘smokers' paradox' was observed in China, and in peer review studies around the world, one of the first was a French study that found that out of 11,000 hospitalised patients, only 8.5 percent were smokers, compared to 25.4 per cent of the general population.
This lead to questions about why: what is it among the hundreds of chemicals in cigarettes that could be protecting people?
Amoura said he and other researchers zeroed in on nicotine.
“Nicotine attaches itself naturally to a receptor in our blood cells, and other cells, and it lowers the immune system’s activity,” he explained.
When researchers have removed the nicotine receptors in mice and then expose them to an infection, their immune systems go out of control, releasing too many cytokines, which in small quantities can help fight infections, but in large quantities, called cytokine storms, can lead to organ failure and death.
Severe Covid infections often result in cytokine storms, which is often what kills patients.
Are nicotine patches the solution?
Last year French researchers analysed public health data of people who used nicotine substitutes, like patches or gum, “and they saw that those people had less Covid than those who did not use them. And they were hospitalised less,” said Amoura.
The Paris public hospitals took the hypothesis that nicotine could play a role in reducing Covid infections, or lowering the severity of cases, and launched three clinical studies using nicotine patches, lead by Amoura.
One of the studies, concluded in April, involved 220 patients in intensive care units for severe Covid. Half were given nicotine patches and the others given placebos. The data is being analysed, and the first results should be out in June.
The other two studies involve patients who are hospitalised, but not in the ICU, and the general population.
Waiting for results
Amoura is still recruiting non-smokers who have not had Covid to participate in the study on the general public.
He hopes the results will prove the hypothesis, and start leading towards a potential treatment for Covid.
"That's what's driving this,” he said. "For now there is no treatment for Covid. There is a vaccine, there is no treatment that works.”
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