Abstract
Emerging infectious diseases are defined as infections that have recently surfaced or have existed but are rapidly increasing in incidence or geographic range. Re-emerging diseases, on the other hand, are those that were once kept under control but have returned because of reduced immunity, vaccine reluctance, or even changes in the environment. It is of concern how emerging and re-emerging viral infections can affect global health, society, and the economy. Vaccination refusal, along with socioeconomic differences, worsens their impact. The process of globalization, urbanization, climate change, and zoonotic spillovers has led infectious diseases to be spread faster than before, and sustained genomic surveillance, molecular diagnostics, and vaccine technologies such as mRNA vaccines greatly improve the ability to respond to viral epidemic outbreaks. Unfortunately, these innovations have not reached many low- and middle-income countries, which demonstrates the increasing distribution of resources these nations desperately need. This review was conducted through a comprehensive literature search of peer-reviewed articles published between 2000 and 2024 using databases such as PubMed, Scopus, and WHO reports. The purpose of this review was to examine the epidemiological factors of viral emergence, the use and implementation of modern technological response systems to viral outbreaks, and the subsequent challenges in global health security. It has given weight to the need for stronger international collaborations, sustainable public health policies for the future, and mitigation strategies that can prevent future pandemics. The global community can effectively prevent the clash with infectious diseases that alter themselves rapidly by providing better research, stronger governance, and infrastructure.

Key words: Viral infections, epidemiological trends, diagnostics, public health interventions, systemic review