Number of participants in various subgroups (eg, comorbidities, premature infants, elderly, immunocompromised) of Hospitalized Patients by Type of Respiratory Pathogen (RSV, influenza A, and hMPV in adults and RSV and hMPV in infants/children less then or equal to (<=) 5 years of age) will be characterized.

Symptoms of Participants Presenting at Hospital (outpatient clinic, emergency room/emergency department [ER/ED], or general ward) and at discharge will be assessed.

Number of participants without presenting symptoms among participants with PCR-confirmed RSV, influenza A, or hMPV infections of ARTI will be reported.

Number of participants with respiratory infections of nosocomial origin with or without presenting symptoms among participants with PCR-confirmed RSV, influenza A, or hMPV infections will be reported.

The number of patients admitted to different hospital-locations (ED/ER department, Ward, Outpatient clinic, ICU, Other), their provenances, the number of patients being transferred to ICU and the number of patients being thereafter re-hospitalized will be assessed.

The distribution of the primary reasons for the index-hospitalization, the distribution of the primary reasons for ICU transfer, the distribution of the criteria used to discharge from the index-hospitalization (including hospital recovery scale (HRS) and oxygen saturation) will be assessed.

The hospital recovery scale assesses a participant's clinical status. The scale provides 6 mutually exclusive conditions ordered from best to worst: 1) not hospitalized; 2) non-ICU hospitalization, not requiring supplemental oxygen; 3) non-ICU hospitalization, requiring supplemental oxygen; 4) admitted to the ICU, not requiring invasive mechanical ventilation; 5) requiring invasive mechanical ventilation; and 6) death.

The NEWS provides guidance for 3 scores: Low score (1-4) should prompt assessment by a competent registered nurse who should decide if a change to frequency of clinical monitoring or an escalation of clinical care is required; Medium score (5-6) should prompt an urgent review by a clinician skilled with competencies in the assessment of acute illness; and High score (7 or more) should prompt emergency assessment by a clinical team/critical care outreach team with critical-care competencies.

Confusion, respiratory rate greater than or equal to (>=) 30/minute, low systolic less than (<) 90 millimeter of mercury (mm Hg) or diastolic less than or equal to (=<) 60 mm Hg blood pressure, age >= 65 years (CRB-65) scoring system at admission to the hospital for adults with lung disease and the relevance on MRU by type of Respiratory Pathogen will be assessed. CRB-65 Scale ranges from 0 to 4. Score 0 = Very low risk of death, Score 1 and 2 = Increased risk of death and 3 or 4 = High risk of death.

The APACHE II is a validated severity of disease classification system. It uses a point score based on initial values of 12 routine physiologic measurements (temperature, mean arterial pressure, heart rate, respiratory rate, oxygenation, arterial pH, serum sodium, potassium, and creatinine, hematocrit, white blood cell count, Glasgow coma score), age, and previous health status to provide a general measure of severity of disease. An increasing score (range 0 to 71) is closely correlated with subsequent risk of hospital death for intensive care admissions.

The SAPS 3 consists of 20 variables: age, co-morbidities, use of vasoactive drugs before ICU admission, intrahospital location before ICU admission, and length of stay in the hospital before ICU admission, reason(s) for ICU admission, planned/unplanned ICU admission, surgical status at ICU admission, anatomic site of surgery, and presence of infection at ICU admission and place acquired, lowest estimated Glasgow coma scale, highest heart rate, lowest systolic blood pressure, highest bilirubin, highest body temperature, highest creatinine, highest leukocytes, lowest platelets, lowest hydrogen ion concentration (pH), and ventilatory support and oxygenation. Score varies from a minimum of 0 points to a maximum of 217 points. Higher scores indicate higher severity.

MRU in adults by type of virus infection (RSV A, RSV B, influenza A, influenza B, hMPV, any other virus infection if available) at baseline that is before hospitalization will be collected.

MRU in adults by eGFR at baseline that is before hospitalization will be collected. The glomerular filtration rate is an indicator of renal function and is calculated based on serum creatinine.

ReSVinet scale is based on seven parameters (feeding intolerance, medical intervention, respiratory difficulty, respiratory frequency, apnoea, general condition, fever) which are assigned different values (from 0 to 3) for a total of 20 points. Higher scores indicate higher severity.

Levels of White Blood cell Count during hospitalization will be reported.

Levels of Neutrophils during hospitalization will be reported.

Levels of Procalcitonin during hospitalization will be reported.

Levels of C-Reactive Protein during hospitalization will be reported.

Levels of Viral Load during hospitalization will be reported.