Predi-COVID is a prospective cohort study composed of people positively tested for COVID-19 in Luxembourg, followed digitally for monitoring participants' health evolution and symptoms at home. Participants will be actively followed for 14 days from the time of confirmation of diagnosis, whether they are at the hospital or at home in isolation or quarantine. Short evaluations will be also performed at week 3 and week 4 and then monthly for a period up to 12 months to assess potential long term consequences of COVID-19. A subsample of 200 participants will be contacted to integrate complementary clinical data and collect samples.

The study aims at identifying factors associated with the COVID-19 disease severity. COVID-19 patients with severity criteria will be compared to patients with mild disease managed at home.

A deep phenotyping related to the symptoms of the disease as well as biosampling allowing for laboratory-based and computational analytics will be performed.

The objective is to recruit virtually all COVID-19 positive persons in Luxembourg.

The sub-sample of a minimum of 200 COVID-19 positive persons in Predi-COVID study would allow to find a risk ratio of severe disease above 2 for the selected risk factor with a power of 80% when the prevalence of the disease is above 7%.

For every symptomatic adult tested positive by RTqPCR, biological samples will be collected at the inclusion and as follow-up 3 weeks after inclusion.

For patients at home, an experienced nurse from CIEC will perform the sampling, using all the required precautions and protections in the actual context.

For hospitalised patients, a simplified sampling strategy will be put in place and adapted to the patient state, the workload of staff and adapted constantly depending on the evolution of the epidemy.

Data will be collected through 3 different ways :

1. Questionnaires : health status monitoring data with daily questionnaires during the 14 first days following diagnosis, weekly questionnaires at week 3 and 4 and monthly questionnaires from month 2 to month 12.
2. Adapted ISARIC eCRF for patients at hospital (during all hospital stay) and at inclusion for patients included from home.
3. Smartphone application (LIH in-house solution) : innovative data (voice recordings, geolocation and mini-questionnaires).

An ancillary study will be added (Predi-COVID-H):

Predi-COVID-H is an ancillary cohort study composed of Household members of index cases to monitor symptoms and disease outbreak in this high-risk population. For every asymptomatic member of the family of a "case" included in the Predi-COVID sub-sample (a "contact"), clinical as well as socio-economic characteristics will be collected. Biological samples will also be collected at the same time as the "case" visit by nurses and up to 30 ml of blood will be taken at baseline, for serology. IgG and/or IgA seropositive "contacts" will be proposed to be enrolled in the Predi-COVID study. For IgG and IgA seronegative "contacts", a second serology will be planned 2 weeks later, up to 30 mL of blood will be collected. If they become IgG and/or IgA seropositive, they will be proposed to be enrolled in the Predi-COVID study. IgG and IgA seronegative "contacts" will be followed digitally

Inclusion Criteria:

• SARS-CoV-2 infection as determined by PCR, performed by one of the certified laboratories in Luxembourg
• Signed informed consent form
• Age ≥18 years old
• Hospitalized or at home

Exclusion Criteria:

• Patients not understanding French or German
• Patients already included in an interventional study on Covid-19 (Discovery or other)

Adult (≥18 years old) patients with confirmed SARS-CoV-2 infection, hospitalized or at home.