Vaccination as a tool to combat introductions of notifiable avian influenza viruses in Europe, 2000 to 2006

Abstract

In late 2000, Italy was the first country of the European Union (EU) to implement an emergency vaccination programme against notifiable avian influenza. Vaccination with a conventional vaccine containing a seed strain with a different neuraminidase subtype from that of the field virus was used to complement biosecurity and restriction measures as part of an overall eradication strategy. This vaccination technique, in line with the Differentiating Infected from Vaccinated Animals system (DIVA), was applied several times until March 2008. This strategy enabled the identification of field exposed flocks and ultimately the eradication of low pathogenic H7N1, H7N3 and H5N2 infections. Italy was also the first country to implement a bivalent H5/H7 prophylactic vaccination programme of defined poultry populations, which was discontinued in December 2006. Following the incursion of highly pathogenic H5N1 into Europe, in 2005 and 2006, two other EU Member States, namely France and the Netherlands, implemented preventive vaccination programmes in 2006 but they targeted selected poultry populations different from those targeted in Italy and were implemented for short periods of time. Data generated during six years of experience with vaccination against avian influenza in Italy indicate that it is a useful tool to limit secondary spread and possibly prevent the introduction of low pathogenic avian influenza viruses in a susceptible population. The experience of France and the Netherlands provides data on vaccination of ducks and hobby poultry respectively and monitoring programmes associated with vaccination and difficulties related to their application. The advantages and disadvantages of vaccination need to be considered in the decision-making process, including the financial aspects of vaccination.

Determinants of Bluetongue Virus Virulence in Murine Models of Disease

“…The incursion of any BTV strain (even a vaccine strain) into a BTV-free area is currently treated as an outbreak by regulatory agencies, with restrictions on animal movements and trade. Thus, by better understanding the determinants of BTV virulence, we may be able to design control strategies that "fit" the risks posed by specific incursions, using an approach similar to that taken for avian influenza or Newcastle disease (1,20).…”

Avian influenza vaccination in Egypt: Limitations of the current strategy

“…However, a carefully conceived vaccination strategy must be accompanied by strict bio-security measures and efficient monitoring systems. Countries which have authorized vaccination to control avian influenza outbreaks under special circumstances in the past have met with contradictory results, from effective control and disease eradication to antigenic drift of the viral strain (Lee et al, 2004; Busani et al, 2009; Capua et al, 2009). Extensive vaccination programs are currently ongoing in South East Asia and Egypt to control the H5N1 HPAI epidemics (Peyre et al, 2009; Domenech et al, 2009).…”

H5-based DNA constructs derived from selected highly pathogenic H5N1 avian influenza virus induce high levels of humoral antibodies in Muscovy ducks against low pathogenic viruses

“…Antibody titres against influenza were also highly variable in a post-vaccination surveillance study in France in 2006. Following vaccination with an inactivated H5N2 vaccine in free-range domestic ducks, sera were collected in flocks where unvaccinated sentinel birds had remained negative and were tested against the vaccinal antigen: HI titres ranged between 0 and 9 log 2 with a mean titre of 6 log 2 [28]. Other experimental studies have shown that vaccination against influenza in ducks with inactivated vaccines eventually requires higher antigen doses and multiple injections to be immunogenic and protective [29].…”