Could your own antibodies make a respiratory infection worse?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: For adult patients : * Patients with acute respiratory failure requiring the administration of oxygen\* to maintain peripheral oxygen saturation at at least 90% \* in patients with chronic respiratory failure, an oxygen flow higher than the usual flow or a duration of non-invasive ventilation longer than the usual duration will be required. * Patients with influenza, RSV or SARS-CoV-2 infection diagnosed by Reverse Transcription Polymerase Chain Reaction (RT-PCR) or antigen test in the last 7 days * Patients hospitalized in participating intensive care units For pediatric patient : * In respiratory distress placed on oxygen with signs suggestive of viral infection: 1. moderate or absent fever or nasopharyngeal congestion or cough 2. signs of acute respiratory distress (polypnea \> 2DS of the normal value, intercostal drawing, thoraco-abdominal sway) with more or less marked hypoxia (SpO2 \< 92% under ambient air), 3. and/or significant apnea (associated with bradycardia or desaturation), 4. and/or dietary difficulties (reduction of rations to less than 50% of the usual ration). * Hospitalized in the pediatric emergency and intensive care unit of Hôpital Femme Mère Enfant (HFME) Exclusion Criteria: * Opposition of the patient or his close family/friend to inclusion in the study * Patient under legal protection measure * Patient who was included in this study during a previous stay * Immunodepression defined by: bone marrow allograft less than 24 months old, chemotherapy for less than 6 months, HIV infection with CD4\<200/mm3 or \<15%, corticosteroid therapy for more than 2 weeks with a daily dose greater than 10 mg of prednisolone equivalent, immunosuppressive treatment administered in the previous 3 months (6 months for rituximab), aplasia, asplenia or splenectomy. * Patient under 30 kg (for adults) and less than 3 kg (for children)