The COVID-19 pandemic has had significant health, social, and economic consequences in France: the research community is fully engaged in identifying all possible ways to prevent transmission.

In some studies, a lower prevalence of smoking has been found among COVID-19 patients or those with positive SARS-CoV-2 serology, compared to the general population. In France, a cross-sectional analysis of data from the EpiCov and Sapris studies in the general population showed a reduced risk of seropositivity among smokers who were surveyed and tested. These studies have led some researchers to hypothesize that nicotine may have a protective effect against COVID-19 infection.

Santé publique France emphasizes that:

• At this stage, the potential protective effect of nicotine is a research hypothesis that must be tested using appropriate protocols that meet the quality criteria for clinical research. Several such protocols have been proposed.

• Observational studies suggesting an underrepresentation of smokers among COVID-19 patients exhibit certain biases, and no causal link can be established:

  • for those based on medical-administrative data, this may involve bias in the collection of current or past smoking behaviors, differences in how smokers and nonsmokers use the healthcare system, confounding factors (sociodemographic characteristics, comorbidities) not accounted for in the analysis, reverse causality between COVID-19 infection and smoking cessation, or differing sensitivity of smokers and nonsmokers to screening tests,

  • for those based on surveys, representativeness is not always guaranteed, as evidenced by the often low smoking prevalence in the surveyed samples, compared to that observed in surveys specifically designed to measure addictive behaviors, such as the Santé publique France Barometer.

To address the question of a possible link between smoking, nicotine, and COVID-19, Santé publique France recommends:

1. The implementation of representative seroprevalence surveys in the general population, i.e., based on a random methodology, providing precise data on the following indicators: current smoking, amount consumed, past smoking (if applicable, date and reason for quitting), exposure to secondhand smoke, use of vaping products (if applicable, with or without nicotine), and use of nicotine replacement therapies. For surveys of this type that have already been conducted, a detailed analysis of the link between smoking behavior and SARS-CoV-2 infection by sex, age, or other variables of interest is necessary. Comorbidities associated with smoking (such as respiratory or cardiovascular diseases) should also be investigated and taken into account in the analyses.

2. The implementation of appropriate and specific research protocols on this topic, particularly longitudinal studies to examine the influence of current or past smoking on the likelihood of SARS-CoV-2 infection, and clinical studies to test the hypothesis of nicotine’s protective effect on both the likelihood of SARS-CoV-2 infection and the course of the disease.

3. Information for healthcare professionals treating COVID-19 patients, to encourage them to exercise increased vigilance when diagnosing COVID-19 in a patient who smokes. Indeed, among those infected with SARS-CoV-2, smoking (current or past) is associated with more severe forms of the disease or its progression. A meta-analysis based on 47 studies involving more than 30,000 patients showed that the risk of severe COVID-19 was 80% higher among smokers (RR=1.80 [1.14–2.85]). Furthermore, conditions (respiratory or cardiovascular) directly linked to tobacco use may themselves be associated with a poor prognosis for the disease.

4. Maintaining smoking cessation support and treatment services for all French smokers, in the context of a health, psychological, economic, and social crisis that could lead to an increase in smoking. The Coviprev study by Santé publique France showed that by the end of March 2020, 27% of smokers reported having increased their tobacco consumption. Primary care providers must remain fully committed to supporting smokers in quitting. In addition, remote support services, such as the 39 89 hotline and the Tabac info service app, have proven effective and are particularly relevant in this context of restrictions on travel and social interactions.