Are current avian influenza vaccines a solution for smallholder poultry farmers?

Abstract

Vaccination against highly pathogenic avian influenza (HPAI) viruses, along with other measures, was successful in eradicating AI in very few countries where the competence of national veterinary services or the geography and bird density have contributed favorably to the outcome. The main constraints to an effective AI vaccination are vaccine composition matching field strains, reliable cold chain and logistics to target all poultry smallholders, constraints related to the availability of sufficient financial and human resources. When not conducted properly, vaccination can also contribute to the emergence of new field viral strains, through genetic drifts of HPAI viruses. While new technologies have improved the possibility to produce high quality vaccines matching field strains, recurrent issues like post-vaccination field surveillance and vaccination coverage continue to limit the relevance of AI vaccination in smallholder settings. A “game-changer” vaccine targeting smallholders should be universal to protect against all field viral strains and reduce significantly, if not totally eliminate, the need for costly post-vaccination surveillance. The ease of administration of this vaccine (eye drop or one single injection) would further contribute to its relevance in the field. These characteristics are considered essential for the product profile of an AI vaccine that can contribute in a meaningful way to the livelihoods of poultry smallholders.

Pros and Cons on Use of Live Viral Vaccines in Commercial Chicken Flocks

“…This is relevant when trying to get a good match between an outbreak virus and the candidate vaccine because the outbreak virus cannot be predicted with any certainty. Efficacy of both live and inactivated AI vaccines in other species, such as ducks, geese and game birds, are limited (39). Despite these factors, innovative experimental live vaccines of AI have been attempted.…”

Promising strategy for developing mRNA-based universal influenza virus vaccine for human population, poultry, and pigs– focus on the bigger picture

“…The current seasonal conventional vaccine technology is egg-based, cell-based, or recombinant. Available conventional vaccines for poultry are based on the following five technologies: The whole AIVs are grown in embryonated chicken eggs which are then chemically inactivated and adjuvanted, HA DNA vaccines, HA protein vaccines or virus-like particles which are produced in insect cells, defective-replicating alphaviruses with H5 gene of AIV, and live virus vectors expressing HA of AIV based on recombinant technologies (e.g., recombinant Newcastle disease virus and Fowl-pox virus) ( 66 ). The influenza vaccines for pigs are also based on traditional– inactivated or killed virus-based technology ( 67 , 68 ).…”

Strategic construction of mRNA vaccine derived from conserved and experimentally validated epitopes of avian influenza type A virus: a reverse vaccinology approach

“…Currently available platforms of avian influenza vaccines include attenuated wild-type avian influenza A viruses (AIAV), protein subunit HA, adjuvanted HA DNA vaccine, and recombinant live virus vectors expressing HA and NA gene inserts. However, aside from the challenges with cost production and limited cold chain capacity, these currently available vaccines are not commonly used because of their reduced vaccination efficacy over time [ 8 ]. Unequivocally, there is a need for constant reformulation of avian influenza vaccines due to antigenic drift and antigenic shift of AIAV in the field.…”