Control of Highly Pathogenic Avian Influenza by Evidence-Based Vaccinology: Past Progress, Future Prospect

Background and Objectives: Highly pathogenic avian influenza (HPAI) viruses are particularly important due to huge economic consequences and public health concerns. During recent years, because of the severity of epidemics and failure in the control and eradication of HPAI, vaccination has been introduced into the National Prevention and Control Program of some countries, including Iran. This article discusses the role of vaccination in the control of HPAI, the characteristics and constraints of the vaccine, types of commercial vaccines, and previous experiences.   Methods: Scientific databases were searched to collect essential evidence on the role of vaccination in controlling HPAI in a variety of poultry and birds with no time and language restrictions. The articles related to the efficacy and effectiveness of the commercial vaccines on at a national level or population-based studies in some farms were included in present study.   Results: Because of the high pathogenicity and variability of the influenza virus as well as the shortcomings of some commercial vaccines in prevention of virus transmission, vaccination should only be taken into consideration when all other methods of disease control are ineffective. The consequences of the use of vaccines containing the seeds non-antigenically matched with the circulating strains have been reported frequently.   Conclusion: In the national vaccination program, informed policymaking requires evidence based vaccinology that can facilitate development of the national infrastructure with awareness of the limitations of commercial vaccines and the realistic expectations of logistic, financial, and human resources.