Emergence of Highly Pathogenic Avian Influenza H5N1 Virus in Humans

Although avian influenza A viruses are highly species-specific, they can occasionally cross the species barrier to infect other species and cause highly lethal disease. In 1997, 18 human cases of H5N1 avian influenza were first reported in Hong Kong. A new outbreak occurred in 2003. Since then, the HPAI H5N1 virus has evolved rapidly. On 26 February 2024, WHO reported the first five laboratory-confirmed human cases in Cambodia, including one death. Since 2003, the new HPAI H5N1 viruses have killed 466 people out of 964 cases. To cause a pandemic, the virus must be antigenically novel, virulent, and transmissible between humans. A pathogen that lacks at least one of these characteristics has the potential to cause a pandemic. Currently, H5 viruses do not have the potential to cause a pandemic because they cannot yet be transmitted from person to person. However, it may take very little time for H5 viruses to acquire pandemic potential. The purpose of this editorial was to express the opinion of the authors on such an important topic given the spread of the avian flu virus around the world. Unfortunately, the COVID-19 pandemic demonstrated our unpreparedness for global disasters. Hence, we should learn lessons from it. At the onset of the 2009 influenza pandemic, WHO considered scaling up the production of live-attenuated influenza vaccine (LAIV) as a promising strategy in a pandemic situation. Unlike inactivated vaccines, LAIVs are capable of inducing broad and long-term immune responses, making them an attractive option for pandemic preparedness, particularly in countries with very high population densities. Global surveillance and pre-pandemic preparedness for defense against H5N1 influenza viruses are public health concerns, which warrant intensive development of potential pandemic vaccines, including LAIV.