The figures are surprising. The proportion of smokers among people infected with SARS-CoV2 is low. A Chinese study published in late March in the New England Journal of Medicine, and involving more than 1,000 infected people, showed that the proportion of smokers was 12.6%, much lower than the proportion of smokers in China (28%).
Other studies point in the same direction. In France, according to data from the Public Assistance-Hospitals of Paris (AP-HP), among the approximately 11,000 patients hospitalized because of Covid-19 in early April, and since the start of the epidemic, 8.5% were smokers – while the daily smoker rate is 25.4% across the country.
Intrigued, like others, by this low rate of smoking patients, Dr. Makato Miyara and Professor Zahir Amoura, from the department of internal medicine at the Pitié Salpêtrière Hospital (AP-HP), and their colleagues went more far. In a study available in prepublication on the site Qeios, on April 20, they compared the rates of daily and occasional smokers in ambulatory patients (with mild symptoms), whose diagnosis of Covid-19 had been confirmed, and in other patients, more serious, hospitalized at La Pitié-Salpêtrière (excluding intensive care services), with the rates of daily smokers in the French population.
“The question on tobacco was asked systematically to these patients; we only have 1.9% missing data, which is plentiful in previous studies published so far “, specifies the epidemiologist Florence Tubach (Pitié-Salpêtrière, Sorbonne University), co-author of this study.
“We rarely see that in medicine”
The results are clear. Of the 343 hospital patients, median age 65 years, 4.4% were daily smokers. And of the 139 outpatients, median age 44, 5.3% were daily smokers. “The main confounders were taken into account, such as gender and age”, specifies Florence Tubach. We know that smoking decreases with age, going from around 30% for those aged 45-54 to 8.8% of women and 11.3% of men aged 65-75, according to the latest health barometer. from the health security organization Public Health France (SpF), which does not go beyond 75 years.
“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”, write the authors. “The effect is significant, it divides the risk by five for ambulatory patients and by four for hospitalized patients. we rarely see that in medicine “, notes Florence Tubach.
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