Study of Socio-demographic Factors, Behaviors and Practices Associated With Infection With SARS-CoV-2 Responsible for COVID-19

The objective of the study is to identify socio-demographic factors, behaviors and practices
associated with infection with SARS-CoV-2 to help determine where and how patients mostly get
infected with SARS-CoV-2.

The study will focus on sociodemographic data (age, gender, location of residence,
socio-economic level, etc.), behaviors and practices (adherence to hand-washing,
mask-wearing, work habits, meetings, etc.), the places they visit (public transportation,
bars, restaurants, sport facilities, etc.).

It is a case-control study including :

- cases identified by the nationwide system of positive SARS-CoV-2 tests (SIDEP)
(currently limited to RT-PCR) and invited to participate by CNAM, which hosts the data
from the nationwide test system, through a nationwide email campaign sent once a week;
cases will be asked if they can tell where they most probably were infected, leading to
a detailed description of the circumstances of the contamination, including whether the
suspected contamination took place within the household or not.

- controls included via Ipsos, a polling institute with access to personal data from a
panel from which they will include controls matched on age (divided into 10-year
categories up to 68 years old included as expected adherence to an online questionnaire
quickly drops beyond that age), gender and geographic area (departement); invitations
will be sent every week via email to adapt the profile of recruited controls to the age,
gender and geographic profiles of the cases that participated in the previous week;

- cases will be offered to invite a person they live with to participate in the study
offering another case-control analysis inside a household. Cases will be recommended not
to invite the person that they suspect was responsible for their contamination, if a
intra-household contamination is suspected. They will indicate the email address of that
person to allow sending of an invitation via email. These participants will be required
to report the result of the test as recommended by contact tracing guidelines to
determine whether they are cases or controls.

Analysis will also include descriptive analysis:

- Estimation of the proportion of cases infected within the household or outside

- Among the cases with a extra-household contamination suspicion, proportion of cases for
whom infection circumstances are known and description of these circumstances

- Proportion of cases for whom no specific circumstance of contamination could be
evidenced.

Questionnaires will focus on the 10 days preceding :

- symptom onset (symptomatic cases)

- day of testing (asymptomatic cases)

- day of symptom onset of the first case within a household (people from the same
household as cases) or testing of the first case if they are asymptomatic

- questionnaire completion (Ipsos-recruited controls)

Participants will be offered at the end of the online self-administered questionnaire to
indicate a phone number. Among those agreeing to do so, a random sample of case-control pairs
and cases of particular interest (eg with specific contamination circumstances) will be
called within two weeks following the online questionnaire for a more detailed telephone
questionnaire to measure reliability of online retrieved data and explore more specific
aspects of SARS-CoV-2 transmission.