Influenza: are we protecting our horses effectively?

This research article reviews prevalent equine influenza prevention measures and highlights the need for continued surveillance and vaccine strain updates to protect horses against the flu effectively. It references findings from France that show 15% of horses tested positive for equine influenza virus (EIV), regardless of their vaccination status. The article also discusses current regulations, the importance of mathematical modeling in disease outbreak management, and the continuation of stakeholder collaboration efforts for the welfare of horses.

Overview of Current Vaccination Measures

• The article starts by appreciating the fact that there hasn’t been a single racing day abandoned due to flu in the UK since 1981, thanks to a mandatory flu vaccination policy introduced by the Jockey Club.
• However, the 2007 Australian horse flu outbreak served as a reminder that equine influenza virus (EIV) is an ever-present threat.

Role of Mathematical Modeling

• According to Daly et al., although mathematical models are dependent on the accuracy of data, they can provide useful insights for prevention and outbreak management.
• The article points out that most flu outbreaks in vaccinated groups of horses are limited in size and that vaccination decreases the occurrence of epidemics.

Challenges of Current Vaccination Measures

• The study acknowledges that although vaccines might work at an individual level, mismatched vaccine strains can lead to large outbreaks.
• The main culprit is the flu virus’ ability to undergo antigenic drift, thereby rendering vaccine strains outdated over time.
• Although vaccines are effective in limiting the severity of symptoms and spread of infection, it states the importance of updated vaccine strains to efficaciously combat the flu.

The Role of Continuing Surveillance

• The World Organisation for Animal Health (OIE) is responsible for recommending appropriate vaccine strains, which is informed by data provided from various surveillance centres across the globe.
• The British Equine Veterinary Association (BEVA) has taken an initiative to ensure that horses are effectively protected by bringing together interested parties and lobbying for improvements.

Actions and Priorities

• Key priorities include revising guidelines and reducing costs for vaccine strain approval, improving education on equine influenza, supporting confidential outbreak reporting, and improving communication between animal health industry and OIE Expert Surveillance Panel on Equine Influenza Vaccine Composition.

Virus Strains and Vaccines

• At the time this research was written, the circulating viruses were of the American lineage, Florida Clades 1 and 2.
• Only Boehringer Ingelheim Vetmedica Inc had a license for an EIV-containing vaccine in the USA and no such equine vaccines were available in the UK or USA with both under OIE’s 2010 recommendations.

Future Considerations

• Despite vaccination, some horses show signs when exposed to natural EIV challenge, highlighting the importance of continued research and regulation updates.
• Differing vaccination requirements by racing authorities across the world and existing regulations for launching new products requires further uniform and streamlined efforts.
• A balanced view from different stakeholders such as surveillance programme leaders, sports regulators, medicines regulators, and the animal health industry is necessary to ensure the effective protection of horses.