INTRODUCTION:
Lassa virus is a zoonotic disease with the possibility of becoming a pandemic. The operability of the Lassa virus response is country-limited despite its shared risk across porous borders in West Africa. These countries support population mobility, informal trade routes, and uneven health system capacity, which complicates surveillance, case management, and contact tracing. All Lassa virus response and resilience tools operate within national systems, which limits their coordinated action during cross-border outbreaks. However, there is limited information on how these tools work across countries.

AIM:
This study examines the cross-border operability of the Strategy Institution System Operations Technology (SIS-OT) tool for Lassa virus surveillance in West Africa.

METHODS:
A qualitative design was used to gather data from selected Lassa-endemic border regions. Data was collected through semi-structured interviews with 10 stakeholders involved in Lassa virus preparedness and response. Participants were selected using purposive sampling to involve roles like public health officers, emergency operations staff, laboratory scientists, and border health officers due to their relevance to cross-border response. About 75 codes were generated, and thematic analysis was used to generate themes with Nvivo 14, which was guided by the SIS-OT framework.

RESULTS:
This study found three themes, one of which is weak cross-border operability across all SIS-OT domains. At the strategy level, national Lassa fever plans were on domestic initiatives, with limited regional harmonisation or shared preparedness targets. Also, there is limited institutional coordination which relys on informal relationships, while regulatory differences limit data sharing and specimen movement. In addition, operational practices showed inconsistent surveillance coordination, unclear cross-border referral pathways, and limited follow-up of mobile contacts. Technological tools demonstrated low interoperability due to divergent surveillance platforms and laboratory information systems. These findings revealed that cross-border operability results from systemic misalignment across strategy, institutional systems, operations, and technology.