Background: Tuberculosis (TB), though preventable and curable, remains a major public health concern worldwide. While elimination of tuberculosis infection (TBI) is critical to TB elimination, TBI continues to represent a substantial public health burden, particularly among household contacts.

In recent years, tuberculosis preventive treatment (TPT) has been recognized as essential to eliminating TB worldwide and is particularly critical for children with TBI or close contacts of individuals with infectious TB. The scale-up of TPT among household contacts has been markedly slow, with only 55% of the coverage target achieved for children under 5 years and only 10% for those over 5 years by 2022, highlighting substantial gaps in preventive intervention implementation.

Community- and home-based approaches are proposed solutions to reduce the gaps in early detection and provision of preventive treatment for household contacts in high-TB-burden settings many of whom remain underserved with the usual standard facility care. A home-based approach has not been well evaluated for its effectiveness in real-world settings to inform policy decisions. Given the limited evidence, this study aims to evaluate the effectiveness of a home-based TB contact investigation and preventive treatment management among child household contacts in southern Ethiopia.

Objective: This study aims to evaluate the effectiveness of a home-based TB contact investigation and preventive treatment management among child household contacts in Gedeo, South Ethiopia.

Methods: A pragmatic, two-arm, parallel, cluster-randomized trial will be conducted in Gedeo, South Ethiopia. The procedures in this trial will be based on eight clinical standards for the diagnosis, treatment, and prevention of TBI, which were defined through a Delphi process by a panel of global experts in tuberculosis care. This trial consists of two study groups: a home-based intervention group and a standard facility-based (usual care) comparison group.

Within the intervention group, health extension workers based at health posts in the catchment areas of the selected clusters will receive training focused on the study procedures-the implementation of standardized TB symptom screening protocols, TPT management and adherence support, and safety assessment and reporting. A routine TB care procedure will be implemented in the facilities randomized to the comparison group in accordance with national guidelines. Index patients will be asked to enumerate and bring all children below 15 years of age for TB screening and initiation of preventive treatment or anti-TB treatment accordingly.

Inclusion Criteria:

• Index patients will be eligible if they are at least eighteen years old, live within the facility's catchment area, have been diagnosed with pulmonary tuberculosis within the last month (either bacteriologically confirmed or clinically diagnosed), report at least one child contact below 15 years of age, and are willing to participate in a home visit and give written informed consent and/or assent.

Exclusion Criteria:

• Children will be excluded if there is evidence of drug-resistant tuberculosis based on Xpert MTB/RIF® results. Additionally, children will be excluded if a pediatrician's clinical assessment identifies a contraindication to TPT, where the anticipated risk is deemed to outweigh the potential benefit of initiating therapy. Furthermore, child contacts currently receiving TPT or treatment for active TB will be excluded.