<p>Viral infectious diseases continue to pose a profound threat to global health security, necessitating a strategic transition from centralized, laboratory-bound diagnostics to scalable and decentralized monitoring systems. This review provides a comprehensive synthesis of the role played by optical biosensors in this transformation, spanning rapid pathogen detection, immune monitoring, and vaccine evaluation. Recent advances in nanotechnology including plasmonic metasurfaces, quantum dots, and graphene-based transducers have empowered the detection of high-risk viruses such as SARS-CoV-2, Ebola, Zika, and Monkeypox with sensitivities frequently comparable to gold-standard molecular diagnostics in controlled laboratory settings. In parallel, the early-stage integration of Artificial Intelligence (AI) and the Internet of Medical Things (IoMT) is facilitating the conversion of passive biosensing components into hybrid optical-digital platforms, paving the way for advanced data processing and personalized immune profiling. Furthermore, we examine the integration of these platforms into point-of-care (POC) diagnostics and longitudinal monitoring, while critically assessing the current translational limitations of wearable bioelectronic interfaces for continuous health surveillance. By addressing existing translational bottlenecks such as scalability, matrix interference, and clinical validation we propose a strategic roadmap for advancing optical biosensors from proof-of-concept prototypes to deployable tools for public health management.</p> Graphical Abstract <p></p>