Equine Influenza Vaccine Response

This report supports the idea that vaccination against influenza every 6 months is protective whether using a killed or MLV product. We are still recommending the use of the intranasal product for its efficacy and low reaction rate.
DrO

Vaccines (Basel). 2020 Jul 10;8(3)
Response of Sport Horses to Different Formulations of Equine Influenza Vaccine.
Entenfellner J1, Gahan J2, Garvey M2, Walsh C3, Venner M4, Cullinane A2.

Author information:
1. School of Veterinary Medicine, Bischofsholer Damm 15, 30173 Hannover, Germany.
2. Irish Equine Centre, Johnstown, Naas, Co. Kildare, W91 RH93 Johnstown, Ireland.
3. Department of Mathematics and Statistics, University of Limerick, V94 T9PX Limerick, Ireland.
4. Pferdeklinik Destedt GmbH, Destedt, Trift 4, 38162 Cremlingen, Germany.
Abstract

The international governing body of equestrian sports requires that horses be vaccinated against equine influenza within 6 months and 21 days of competing. The aim of this study was to compare the antibody response of young sport horses to six-monthly booster vaccination with equine influenza vaccines of different formulations. An inactivated vaccine was allocated to 35 horses and subunit and recombinant vaccines were allocated to 34 horses each. After vaccination, all horses were monitored for evidence of adverse reactions. Whole blood samples were collected at the time of vaccination and on nine occasions up to six months and 21 days post vaccination. Antibodies against equine influenza were measured by single radial haemolysis. Transient fever and injection site reactions were observed in several horses vaccinated with each vaccine. Only two horses failed to seroconvert post booster vaccination but there was a delayed response to the recombinant vaccine. The antibody response to the recombinant vaccine was lower than that induced by the whole-inactivated and subunit vaccines up to three months post vaccination. Thereafter, there was no significant difference. By six months post vaccination, the majority of horses in all three groups were clinically but not virologically protected. There was minimal decline in antibody titres within the 21-day grace period.