Severe acute respiratory infections (SARIs) represent one of the leading causes of hospitalization and mortality worldwide. These infections are associated with substantial in-hospital mortality and often constitute a turning point in the medium-term prognosis of older patients and those with comorbid conditions.

SARIs are most frequently of viral origin, involving well-known pathogens such as Orthomyxoviridae (influenza A and B viruses), Pneumoviridae [(respiratory syncytial virus (RSV), human metapneumovirus (hMPV)], Paramyxoviridae [parainfluenza viruses (PIV)], adenoviruses, or rhinoviruses, as well as emerging viruses such as pandemic influenza strains and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the COVID-19 pandemic.

Age-related immune decline (immunosenescence) increases the risk of severe forms and related respiratory or cardiovascular complications. However, the prevalence and burden of the different viral etiologies of Severe acute respiratory infections (SARIs) in older adults remain limited and insufficiently characterized.

The primary objective is to determine the proportion of viral respiratory infections attributable to polymerase chain reaction (PCR)-confirmed pathogen agents among hospitalized older subjects (≥60 years old).

This is an observational, prospective, multicentre study in hospitalized older patients (≥60 years old) who have undergone viral respiratory sampling (RT-PCR or multiplex RT-PCR).

Subjects will be recruited over a period of 24 months at approximately 20 centres. Each subject will participate in the study for 3 months (Screening/inclusion visit and 3-month follow-up phone calls post hospital discharge). A respiratory sample (nasopharyngeal or nasal swab, oropharyngeal swab, aspirate, or bronchoalveolar lavage fluid) will be collected as part of standard of care and analysed by the local virology laboratory for the detection of respiratory virus(es) responsible for the infection, using validated Reverse transcription polymerase chain reaction (RT-PCR) or multiplex RT-PCR assays.

Inclusion Criteria:

• Hospitalized subjects aged ≥ 60 years
• A respiratory sample collected and tested by polymerase chain reaction (PCR) during hospitalisation as part of standard of care

Note: Reasons for PCR:

1. Patients with Severe acute respiratory infection (SARI)

2. Patients with symptoms other than SARI

3. Systematic PCR testing (in the context of clusters or during the winter season) * Recent onset of at least one general symptom and at least one functional or physical respiratory sign

   • General symptoms: fever (which may be absent in older patients), chills, sweating, headache, malaise, myalgia, arthralgia, fatigue, decline in general condition (asthenia, weight loss, anorexia, confusion, or dizziness), digestive disturbances.
   • Respiratory signs: sore throat, rhinorrhoea (common cold), cough, wheezing, dyspnoea, chest pain, or recent auscultatory abnormalities (diffuse or focal).
   • Subjects willing to participate, with a non-opposition form completed and signed by the qualified and trained healthcare professional responsible for providing the participant information
   • Subject affiliated to a health insurance system

Exclusion Criteria:

• Subjects refusing to participate

• Subjects admitted to palliative care unit.

  • Subjects under guardianship
  • Any condition that, in the opinion of the investigator, may interfere with the aim of the study or wellbeing of the patient

Hospitalized older patients (≥60 years old) tested for PCR as part of standard of care (SoC). Subjects meeting the eligibility criteria will be invited to participate in the study.