Evaluation of Current Equine Influenza Vaccination Protocols Prior to Shipment, Guided by OIE Standards

Abstract

To facilitate the temporary importation of horses for competition and racing purposes, with a minimum risk of transmitting equine influenza, the World Organisation for Animal Health (Office International des Epizooties, or OIE), formally engaged in a public–private partnership with the Federation Equestre Internationale (FEI) and the International Federation for Horseracing Authorities (IFHA) to establish, within the context of existing OIE standards, a science-based rationale to identify the ideal time period for equine influenza vaccination prior to shipment. Field trials using vaccines based on different technologies were carried out on three continents. The antibody response post-booster vaccination at intervals aligned with the different rules/recommendations of the OIE, FEI, and IFHA, was monitored by single radial haemolysis. It was determined that 14 days was the optimum period necessary to allow horses adequate time to respond to booster vaccination and for horses that have previously received four or more doses of vaccine and are older than four years, it is adequate to allow vaccination within 180 days of shipment. In contrast, the results indicate that there is a potential benefit to younger (four years old or younger) horses in requiring booster vaccination within 90 days of shipment, consistent with the current OIE standard.

An Overview of Equine Influenza in South America

“…As previously described, EI outbreaks that occurred in South America, from 1963 to the present, seem to be due to introducing new viruses into susceptible horse populations, probably through the movement of subclinically infected horses, especially at the international level, furthermore, facilitated by the short quarantine periods for horses traveling for competitions or sales [ 5 , 44 , 60 ]. The movement of horses for competition, reproductive and recreational purposes between Chile, Argentina, Uruguay and Brazil, is frequent, accelerating the spread of the virus in the region.…”

“…Vaccination plays a major role in controlling EI infection and disease, and particularly for horses that travel frequently, intermingle with other horses and participate in shows, sport and competition events [ 5 , 6 , 37 , 61 ]. Almost in all South American countries, EI vaccination is mandatory for mobile or congregate equine populations [ 54 , 62 ].…”

“…This is due to the highly contagious nature of the causative agent, the equine influenza virus (EIV) [ 1 , 2 , 3 ]. EIV is endemic worldwide except for Iceland and New Zealand, where it has never been reported, and Australia, which is currently free again, after the first incursion of EI in 2007 [ 2 , 4 , 5 ]. Outbreaks of EI are associated with the commingling of horses for competitions and other equestrian events and with the international movement of horses [ 4 , 6 , 7 ].…”

Response of Sport Horses to Different Formulations of Equine Influenza Vaccine

“…This study compared the antibody responses to commercial equine influenza vaccines for six months following a biannual booster. A subset of the serology results were previously included in a global project to establish within the context of existing OIE standards, a science-based rationale to identify the ideal time period for equine influenza vaccination prior to shipment [ 19 ]. The current study focused on a comparison of vaccine performance including adverse effects in a population consisting of young regularly vaccinated sport horses.…”

Immunogenicity of inactivated Equine Influenza (H3N8) virus vaccine with different adjuvents in equine

“…Diseased horses and recovered ones without any complications must give a supportive care for one week/every feverish day to allow regeneration of the mucociliary apparatus (Bonnie and Dacvim, 2014) . Vaccination is the most efficient defense mechanism against EI disease (Cullinane et al, 2020). The vaccination aims to decreasing clinical signs and the convalescence period of the disease as well as reduction of the likelihood of secondary infection (Paillot et al, 2013 andFougerolle et al, 2019).…”