Virus Inactivation Using a High Dose of Gamma-Irradiation: A Possible Approach for Safer Vaccines Against Highly Infectious Agents

Vaccination is arguably the most crucial protection strategy available against infectious agents. The World Health Organisation (WHO) estimates immunisations against the pathogens diphtheria, pertussis, tetanus, and measles avert 2-3 million deaths every year [1]. However, despite our advanced knowledge and the availability of highly effective vaccines against many diseases, several infectious agents, such as influenza A virus, continue to be a major scientific challenge. Accumulating reports of human infection with Avian influenza strains H5N6, H7N9, H9N2, and the highly pathogenic H5N1 illustrate a major public health concern. Current seasonal influenza vaccines will not protect against newly emerging pandemic strains if they acquire efficient human-human transmission and disseminate through the population. In fact, commercially available inactivated vaccines against influenza A virus confer strain specific antibody-mediated protection only, and require annual reformulation to accommodate for the frequent emergence of antigenically distinct strains. In addition, the WHO recommendation for flu vaccine formulation is based on an educated-guess approach guided by WHO surveillance of recent virus activity. Our recent encounter with the pandemic pH1N1 influenza A virus in 2009 illustrates the inability of current flu vaccination strategies to control novel emerging and pandemic strains. The time required to manufacture new vaccines based on newly arising strains similarly limits the effectiveness of current strategies. These shortcomings highlight the need for a new approach to develop flu vaccines that are capable of providing protection against emerging strains.