A Rapid Triage Test to Improve Risk-stratification of Febrile Children (EChiLiBRiST, Clinical Trial 1, Outpatients)

This is a multi-country, open label, two-arm, parallel-group, superiority, individually randomised clinical trial involving 2,606 febrile children per country (two countries, total n=5212). The trial will compare the performance of a point-of-care rapid triage test (POC-RTT) based on suPAR levels (i.e.suPARnostic®) (in combination with IMCI-based strategies, which are the SoC) to appropriately support admission/referral vs discharge decisions during the first clinical assessment of febrile children aged 2-\<60 months compared to the standard of care based on IMCI guidelines.

Febrile children meeting the study eligibility criteria will be randomly allocated (1:1) to one of the two triaging approaches (arms): 1) IMCI-based standard of care (SoC); or 2) IMCI-enhanced by suPAR levels (SoC + suPAR POC). Blood will be collected from all participants and only those randomised to the intervention arm (arm 2) will have suPAR levels determined at the POC using suPARnostic® device.

At baseline, all children will undergo two clinical assessments. Primary composite endpoint of "appropriateness of discharge" will be based on the first clinical assessment, which is more representative of real-world clinical practice. However, the ultimate decision on admission/referral vs discharge will be based on the second clinical assessment, which will ensure the safest possible clinical practice in the context of a clinical trial.

1. At baseline, during the first clinical assessment, all participants will be evaluated following the SoC based on IMCI guidelines, which will guide management decisions, including clinical diagnosis and treatment. This IMCI-guideline based evaluation during this first clinical assessment will be conducted by a health worker as per routine clinical practice in the outpatient departments of each study site.

1. In the participants randomised to the control arm, decision of admission/referral vs discharge home will be informed by IMCI-based evaluation alone (SoC). 2. In the participants randomised to the intervention arm, decision of admission/referral vs discharge home will be informed by IMCI-based evaluation enhanced by suPAR levels (SoC + suPAR POC). Clinicians will be instructed to admit for further observation any child with suPAR levels equal or superior to 4 ng/mL (except for confirmed malaria, that it will be equal or superior to 6 ng/mL), as these patients are at moderate or high risk of adverse outcomes and death. On the other hand, children with suPAR levels below 4 ng/mL (or below 6 ng/mL in case of confirmed malaria) will be eligible for discharge home at the criteria of the clinician, considering the signs and symptoms found, and based on IMCI guidelines. Hence, should clinicians in charge deem that any of these children still require admission, they will be instructed to continue with the admission regardless of suPAR levels.

The study intervention will be implemented during the first clinical assessment, and consequently, primary composite endpoint of "appropriateness of discharge" will be based on the decision of admission/referral vs discharge home during this first clinical assessment, which is more representative of routine clinical practice in each study site. 2. All randomised participants will be also evaluated by an independent study physician in a second clinical assessment, for the implementation of a systematised clinical evaluation (IMCI-based) to uncover any danger signs or severity criteria potentially missed or misinterpreted during the first assessment. This second assessment will also include clinical variables of the clinical scores ED-PEWS, LqSOFA and LODS, as well as temperature and oxygen saturation measures. Hence, study clinicians during this second clinical assessment might be able to uncover more symptoms and signs that are admission criteria due to the tools available in the context of this clinical trial. Initially discharged patients from both arms showing a danger sign during this second assessment will be admitted, as well as those from the intervention arm with suPAR high-risk (red light) and moderate-risk (yellow light) levels, in case that the first clinician might not have adhered to the protocol during the first assessment. On the other hand, this second assessment will not overturn the decision of the first clinician if admission has been decided in case of low-risk (suPAR levels below 4 ng/mL; or below 6 ng/mL in case of confirmed malaria).

This second clinical assessment will guide the ultimate decision on admission/referral vs discharge in order to ensure the safest possible clinical practice in the context of a clinical trial.

Moreover, those participants with respiratory symptoms will be eligible for the respiratory tract infection (RTI) sub-study, where digital lung auscultations, a mid-turbinate nasal swab and a saliva sample will be collected.

Throughout the study, all participants will receive treatment as per the routine clinical practice and SoC for each diagnosis at each study site, administered by clinical staff routinely working in the participating facilities.

All participants will have follow-up evaluations by study clinicians on days 3 and 7 post-enrolment, or at any time in-between in case of clinical deterioration according to caregivers' evaluation. All participants will be also followed-up on day 28 for an interview to follow-up on serious adverse events (SAEs), as well as to collect information on secondary consultations and hospitalisation, or death. A follow-up extra visit at day 91 (month 3) can be conducted for an interview to ask for hospitalisation or death.

• Secondary consultations or admissions [Time frame: Up to day 28]
• Mortality [Time frame: Up to day 28]
• Referrals to higher level facilities [Time frame: Up to day 28]
• Severe disease [Time frame: Up to day 7]
• Symptoms duration [Time frame: Up to day 28]
• Hospital stay length [Time frame: Up to day 28]
• Serious adverse events [Time frame: Up to day 28]
• Discharge in the major aetiological diagnosis [Time frame: Up to Day 28]
• Biomarkers reduction of outcomes [Time frame: Up to Day 28]
• Admissions in the routine care [Time frame: Up to Day 28]
• Biomarkers in admitted [Time frame: Up to Day 28]