H5N1 Avian Influenza: A Narrative Review of Scientific Advances and Global Policy Challenges

Abstract

The H5N1 avian influenza virus continues to evolve into genetically diverse and highly pathogenic clades with increased potential for cross-species transmission. Recent scientific advances have included the development of next-generation vaccine platforms, promising antiviral compounds, and more sensitive diagnostic tools, alongside strengthened surveillance systems in both animals and humans. However, persistent structural challenges hinder global readiness. Vaccine production is heavily concentrated in high-income countries, limiting equitable access during potential pandemics. Economic and logistical barriers complicate the implementation of control strategies such as vaccination, culling, and compensation schemes. Gaps in international coordination, public communication, and standardization of protocols further exacerbate vulnerabilities. Although sustained human-to-human transmission has not been documented, the severity of confirmed infections and the rapid global spread among wildlife and domestic animals underscore the urgent need for robust preparedness. International organizations have called for comprehensive pandemic response plans, enhanced multisectoral collaboration, and investment in targeted research. Priorities include expanding surveillance to asymptomatic animal hosts, evaluating viral shedding and transmission routes, and developing strain-specific and universal vaccines. Strengthening global cooperation and public health infrastructure will be critical to mitigate the growing threat of H5N1 and reduce the risk of a future influenza pandemic.

Keywords: One Health; avian influenza H5N1; pandemic preparedness; sustainable health systems; zoonotic transmission.

Figure 1

Zoonotic transmission and host adaptation pathways of H5N1 clade 2.3.4.4b. The virus primarily circulates in wild and domestic birds, with direct transmission to several mammalian species, including cattle, cats, and wildlife. Pigs are considered potential mixing hosts. Spillover events into wild mammals such as foxes, seals, and bears have been documented. Confirmed zoonotic transmission to humans has occurred, but there is no evidence of sustained human-to-human spread [25,27,30,33]. Created in https://BioRender.com.