Unlike other respiratory viruses such as influenza and Respiratory Syncytial Virus (RSV) where the child is the essential reservoir and central vector of intrafamilial contamination, the child is likely to be a small player in the transmission of Severe Acute Respiratory Syndrome CoronaVirus 2 (SRAS-CoV2) infection. This study aims to describe the age category of the first contact, within 14 days before the appearance of the first symptoms of the index case in order to describe the age categories of this first contaminant, globally, in the group of children and finally in the group of adults. This work is intended to provide food for discussion and to justify the distancing and containment measures imposed on children when their isolation has a deleterious impact that has now been established for some children.

Inclusion Criteria:

1. Children after hospitalized in Hospices Civils de Lyon with Polymerase Chain Reaction (PCR) positive SARS-CoV2,

2. Adults hospitalized in Hospices Civils de Lyon and included in the NOSO-COR study with matching criteria described below.

   • Matching will be performed on family age characteristics and on the period of contamination included in the containment period to minimize bias, and if possible frequency matching according to admission in Intensive Care Unit ICU/Pediatric Intensive Care Unit (PICU), and to family structure (n of children / n of adults in the family).

Exclusion Criteria:

1. Any patient suspected of nosocomial infection.
2. Any patient death during the Covid-19 infection.
3. Any adult patient without children living home.
4. Opposition to participate.

Hospital-based population of children and adults:

• Hospitalized children, 0 to 17 years of age, 25 subjects, consecutive sample survey
• Hospitalized adults, 18 years and above, 50 matched subjects