Field trial for assessment of avian influenza vaccination effectiveness in Indonesia

Abstract

The aim of this field study was to determine the efficacy of vaccination against highly pathogenic avian influenza (HPAI) virus strain H5N1 in Indonesia. A limited, prototype clinical trial was performed using a standardised treatment group, in which poultry flocks were vaccinated at least twice with a selected H5N1 vaccine, and a control group comprising flocks treated with nonstandardised procedures chosen by the farmer. Each group consisted of six flocks comprising either layers or native chickens. Haemagglutination inhibition (HI) antibody levels were determined by regular serum sampling, and outbreak surveillance relied on non-AI-vaccinated sentinel birds. After three vaccinations high antibody titres were produced in the treatment group, and the percentage of layers with an HI titre > 40 was approximately 90%. Although no conclusions can be drawn regarding reduction of virus transmission, this study demonstrated that 11 farms remained free from AI during the observation period, and that a surveillance programme based on differentiating infected from vaccinated animals (DIVA) can be implemented.

Recombinant M2e Protein-Based ELISA: A Novel and Inexpensive Approach for Differentiating Avian Influenza Infected Chickens from Vaccinated Ones

“…The continuous presence of H5N1 in the environment has considerable veterinary and social consequences. Due to devastating losses of H5N1 in most poultry, life-long vaccination of commercial poultry has become a necessity [2], [3], [4]. H5N1 is also a zoonotic agent which has caused human death in number of countries through direct contact of human with infected poultry [5], [6].…”

Antibody Titer Has Positive Predictive Value for Vaccine Protection against Challenge with Natural Antigenic-Drift Variants of H5N1 High-Pathogenicity Avian Influenza Viruses from Indonesia

“…In the field, this translates into reduced environmental contamination and reduced farm-to-farm spread (1,(10)(11)(12)(13). Furthermore, the integration of H5N1 vaccine usage with other control components in poultry has been associated with a reduction in human cases in Vietnam and Hong Kong and a lack of H5N1 HPAI outbreaks on farms on which poultry were fully vaccinated (10).…”

“…However, by mid-2005, reports of vaccine failures emerged from the field in Indonesia (11). The cause of such failures was unknown, but vaccine quality, seed strain selection, and antigen content, as well as field application issues, could result in vaccine failures.…”

A single vaccination of commercial broilers does not reduce transmission of H5N1 highly pathogenic avian influenza

“…An indication for this is that on several poultry collecting facility houses in Jakarta, where spent layers and broilers were collected shortly before slaughtering, H5 virus was isolated [8,19]. Another indication is the observation of an H5N1 outbreak in a vaccinated commercial layer flock [20]. …”

“…Focus was on key epidemiological parameters such as the transmission rate parameter, the infectious period, the generation interval, and the reproduction number [22-24]. Estimation of these parameters in the field is possible, but difficult even in endemically infected areas [20]. Experimental transmission studies offer the opportunity to quantify these parameters under well-controlled conditions [4,25].…”