The purpose of this case-control study is to assess the association of the current and former consumption of tobacco and nicotine in the risk of acquisition of severe acute respiratory syndrome 2 (SARS-CoV-2). the investigators will send a structured interview by mail regarding use of tobacco and nicotine to 2500 healthcare workers (1250 cases with a positive Real Time Polymorphism Chain Reaction (RT-PCR) and 1250 controls with a negative PCR) who were tested in Paris for in March and April, 2020. OR will be estimated by conditional logistic regression modelling with matching for sex and age.

The negative impact of tobacco use on lung health is widely recognized, together with poorer response to several infections. Smoking behaviour is characterized by inhalation and repetitive hand-to-mouth movements which could contribute to virus acquisition. In the context of SARS-CoV-2 outbreak, smoking appears to be associated with negative progression and adverse outcomes. On the other hand, several epidemiological studies suggest that the risk of infection with SARS-CoV-2 is significantly lower (OR 0.3) among current smokers, and this negative association remains significant after adjustment for age or occupation. An hypothesis is that the expression of the gene encoding for angiotensin II conversion enzyme-2-receptor could be down-regulated by nicotin. However several bias in these retrospective epidemiological studies limit their strength. Few informations are available among former smokers and users of alternative nicotine delivery systems.

In March 2020, at Hotel Dieu Hospital in Paris the investigators opened a center for SARS-CoV-2 screening, with nasopharyngeal swabs and RT-PCR, for healthcare workers who had symptoms compatible with SARS-CoV-2 (i.e. fever, chills, headaches, dry cough, anosmia, ageusia, diarrhea). No severe cases were tested. So far, more than 8000 healthcare workers had been tested, among which 40% were positive.

The aim of this study is to perform a case-control study in healthcare workers who underwent SARS-CoV-2 RT-PCR, in which cases are infected with a positive RT-PCR and controls are negative. Cases and controls will be matched for sex and age. In order to obtain with > 80% probability an OR < 0.6, the investigators estimated that the number of subjects to be included is 1250 cases and 1250 controls. A structured questionnaire assessing current and former tobacco consumption and alternative nicotine delivery systems will be sent by mail to cases and controls. Informed consent will be obtained by mail.

OR will be estimated by conditional logistic regression modelling with matching for sex and age.

Such a case-control study will elicit relevant information about the role of tobacco and nicotine use in the risk of acquisition of SARS-CoV-2.

Inclusion Criteria:

• Healthcare workers with mild symptoms of COVID-19 tested with RT-PCR in nasopharyngeal swabs:

  • Cases : positive RT-PCR
  • Controls : negative RT-PCR

• Informed consent obtained by e-mail.

Exclusion Criteria:

• no available e-mail address
• age < 18
• no answer to the structured questionnaire

Healthcare workers tested for SARS-CoV-2 in Hotel Dieu Hospital in Paris in March, 2020