This observational diagnostic validation study aims to evaluate the clinical performance of novel lateral flow and microfluidic-based technologies for the detection of upper and lower respiratory tract infections in children and adults presenting with respiratory symptoms in Uganda, Ethiopia, and Senegal. The main questions it aims to answer are:

1. whether the novel multiplex lateral flow tests and point-of-care microfluidic platform demonstrate sufficient sensitivity and specificity for detecting respiratory pathogens compared with standard laboratory reference methods, and
2. whether these technologies are feasible and usable in low-resource clinical settings.

Participants presenting with suspected respiratory tract infections as part of routine clinical care will provide respiratory and blood samples for diagnostic testing and biobanking, and demographic and clinical information will be collected during a single study visit. Some adult participants and community stakeholders will also complete surveys or interviews regarding the acceptability of biobanking and diagnostic implementation.

The HOLICARE Clinical Trial (Clinical validation of novel Lateral Flow and microfluidic-based technologies for the detection of Upper and Lower Respiratory Tract Infections) is a multicentre study designed to evaluate innovative point-of-care diagnostic technologies for Respiratory Tract Infections (RTIs). Conducted across 11 clinical sites in Uganda, Senegal, and Ethiopia, the study aims to validate rapid diagnostic tools that can support timely identification and differentiation of viral and bacterial respiratory infections in both primary care and hospital settings. The trial will enrol symptomatic children aged 6 months to 17 years and adults aged 18 years and older presenting with suspected RTIs, including symptoms such as fever, new cough, loss of taste or smell, or fast or difficult breathing.

The objectives for sub-study one are as follows:

Primary objective:

To determine the diagnostic performance, including sensitivity and specificity of the multi-LFT using a nasopharyngeal (NP) swab, with results interpreted via both visual detection and an Android tablet as a reader.

Secondary objective:

1. To determine the feasibility of using the multi-LFT in primary care settings to provide basic information for rapid screening and triage.
2. To assess the acceptability of biobanking patient samples for diagnostics and biomedical research through a patient exit/end-of-visit survey [and in-depth semi-structured interviews and focus group discussions] with community stakeholders.
3. To determine the concordance between results obtained via visual interpretation and the Android tablet application.

The objectives for sub-study 2 can be found below:

Primary objective:

To validate the clinical performance, sensitivity and specificity of a POC platform that performs pathogen detection (bacteria, fungi) using microfluidic Loop-mediated Isothermal Amplification (LAMP) and quantification of host-response biomarkers using a bead-based immunoassay, by comparing its results to those of reference standard methods: benchtop Polymerase Chain Reaction (PCR) and Enzyme Linked Immunosorbent Assay (ELISA), respectively.

Secondary objectives:

1. To assess whether the POC-Instrument can be inserted in the patient management procedure to assist clinical decision-making.
2. To assess the hands-on usability of the POC-Instrument and receive feedback by end-users for future implementation in clinical practice.
3. To assess the acceptability of biobanking patient samples for diagnostics and biomedical research through a patient exit/end-of-visit survey (and in-depth semi-structured interviews and focus group discussions) with community stakeholders.

The study consists of two complementary sub-studies.

Sub-Study 1 focuses on Upper Respiratory Tract Infections (URTIs) and evaluates the diagnostic performance of a multiplex lateral flow test capable of simultaneously detecting Influenza A/B, Respiratory Syncytial Virus (RSV), and COVID-19 from nasopharyngeal swabs. Results will be interpreted both visually and using an Android tablet reader to determine the sensitivity, specificity, and feasibility of the test for rapid screening and triage in primary care settings. Approximately 960 participants will be enrolled to achieve the required number of positive cases for each viral target and to assess concordance between visual and digital interpretation of results.

Sub-Study 2 focuses on Lower Respiratory Tract Infections (LRTIs) and evaluates a novel point-of-care instrument that combines microfluidic Loop-mediated Isothermal amplification (LAMP) for pathogen detection with a bead-based immunoassay to quantify host-response biomarkers. This platform is designed to detect and differentiate targeted bacterial and fungal pathogens while also distinguishing bacterial from non-bacterial infections. The clinical performance of the device will be compared with reference laboratory methods, including PCR and ELISA, in approximately 1,200 participants.

Participants will be recruited at participating hospitals and health centres and must present with at least two respiratory tract infection symptoms during screening. Participation will not alter routine clinical care, and eligible patients will provide written informed consent (or assent with parental/guardian consent for children). For Sub-Study 1, sample collection includes two nasopharyngeal swabs for lateral flow testing and an additional swab for PCR analysis. For Sub-Study 2, sputum is the primary sample collected, with bronchoalveolar lavage samples obtained from a limited number of patients where clinically appropriate. If sputum or BAL samples cannot be obtained, a nasopharyngeal swab may be collected as an alternative for testing on the point-of-care instrument. Saliva and blood samples will also be collected for biobanking to support future diagnostic and biomedical research in both sub-studies. In addition to evaluating clinical performance, the study will assess the usability of the diagnostic technologies, their integration into clinical workflows, and the acceptability of sample biobanking among patients and community stakeholders.

Inclusion Criteria:

• Age ≥ 6 months
• Presentation with suspected respiratory tract infection and at least two of the following symptoms:
• Fever (axillary temperature ≥37.5°C) or history of fever
• New acute cough episode
• Shortness of breath
• Tachypnoea (fast breathing)
• Loss of smell and/or taste
• Ability to provide written informed consent (or assent with parent/guardian consent for minors)
• For infants (≤1 year), both fever and new acute cough must be present at screening

Exclusion Criteria:

• Refusal or inability to provide informed consent/assent
• Refusal to provide study samples
• Severe chronic medical conditions or mental incapacity that, in the opinion of the clinician, would interfere with study participation
• Hospitalisation within the previous 2 weeks for reasons unrelated to the current respiratory symptoms
• Acute injury, trauma, or poisoning interfering with participation
• Chronic cough lasting >2 weeks, unless tuberculosis is suspected in the LRTI cohort
• Antibiotic use within the previous 2 weeks for participants enrolled in the LRTI cohort (Sub-study 2) only

The study will enrol symptomatic children aged 6 months to 17 years and adults aged ≥18 years of both sexes presenting to participating hospitals and health centres with suspected upper or lower respiratory tract infections (RTIs). Participants will be recruited in Uganda, Ethiopia, and Senegal from outpatient and inpatient healthcare settings. Eligible participants will present with at least two symptoms consistent with respiratory infection, such as fever, acute cough, shortness of breath, tachypnoea, or loss of smell and/or taste. Participants (or parents/guardians for minors) will provide written informed consent prior to enrolment.