Demand by Experts for Return of Bi-Annual Flu Jabs

Following the recovery of the vaccination shortages experienced earlier in the year, Equine Veterinary Journal (EVJ) has published a report reviewing the science behind flu vaccination schedules, “in particular the replacement of annual boosters with a mandatory bi-annual vaccination programme” and stating that owners must be encouraged to vaccinate horses every six months against equine influenza (EI) for “optimal” protection, as vaccine supplies return to normal.

Mandatory flu vaccination was introduced in most competitive equestrian disciplines some 40 years ago, since when the scale and numbers of outbreaks have in general been relatively small. It is also now a common requirement for many livery yards to help reduce the risk of infectious disease outbreaks on their yards.

Yet outbreaks such as those in the UK in 1989, 2003 and 2019 have “demonstrated EI’s epidemic potential, even in vaccinated horse populations”. In the article Equine influenza bi-annual boosters: what does the evidence tell us? epidemiologists Victoria Colgate and Richard Newton “discuss what has been learnt from previous outbreaks and explain the evidence from mathematical models to show why bi-annual boosters are beneficial”, stating that annual boosters leave a potential immunity gap not only for the individual equine, but others in their immediate environment. The article adds that ideally, vaccine strains should be kept updated to ensure the most relevant disease strains are included but “this is a slow and expensive process for equine vaccine manufacturers”.

The authors added: “The equine industry must surely remain resolute and guided by scientific principles. The clear evidence from experimental, epidemiological and mathematical modelling studies shows why we must encourage clients to revert to a schedule of bi-annual boosters.

“We must also remind horse owners that animals already on six-monthly vaccination regimes were best positioned for the vaccine shortage with a built-in tolerance in their vaccination schedule; their levels of immunological protection would not be expected to decline to susceptible levels, even with a slight delay before being re-vaccinated.”

“Although the recent EI vaccine shortage has necessitated a temporary relaxation of competition vaccine schedules, we must now renew the message that six-monthly boosters are optimal and necessary,” said EVJ editor Celia Marr.

The governing bodies in the UK have not yet announced their flu vaccination rules for 2023.