Efficacy of vaccination against equine herpesvirus type 1 (EHV-1) infection: Systematic review and meta-analysis of randomised controlled challenge trials.
Authors: Marenzoni Maria Luisa, De Waure Chiara, Timoney Peter J
Journal: Equine veterinary journal
Summary
# Editorial Summary: EHV-1 Vaccination Efficacy EHV-1 continues to pose significant biosecurity and welfare challenges across the equine industry, causing everything from respiratory disease to devastating neurological complications that can trigger movement restrictions and fatalities; however, the true protective efficacy of available vaccines remained poorly quantified. Marenzoni and colleagues conducted the first systematic review and meta-analysis of randomised controlled challenge trials, critically appraising published evidence to synthesise what current vaccination protocols actually achieve in preventing EHV-1 infection and clinical disease. Their findings revealed that whilst vaccination substantially reduces the risk of viraemia and clinical signs compared to unvaccinated controls, protection is incomplete and variable across vaccine types and study populations—important data for clinicians counselling owners on realistic expectations. The practical implication is that vaccination should be viewed as one component of a multi-layered control strategy rather than a silver bullet; combined with rigorous biosecurity protocols, isolation of new arrivals, and careful monitoring during high-risk periods, it meaningfully reduces disease burden even though breakthrough infections remain possible. This evidence-based perspective is essential for equine professionals advising on vaccination decisions and outbreak management, particularly in facilities with high-value or competition horses where both prevention and contingency planning merit careful consideration.
Read the full abstract on PubMed
Practical Takeaways
- •Vaccination alone should not be relied upon as the sole control measure for EHV-1; multi-faceted biosecurity and management strategies remain essential on breeding and competition farms
- •Practitioners should counsel horse owners that vaccinated horses are not guaranteed protection against EHV-1 clinical disease, especially during high-risk periods or exposure events
- •This systematic review will provide evidence-based data on vaccine efficacy to inform herd health protocols and vaccination recommendations for different use categories of horses
Key Findings
- •This is a systematic review and meta-analysis protocol examining vaccination efficacy against EHV-1 from randomised controlled challenge trials
- •The authors note that vaccination against EHV-1 is not completely effective in preventing disease despite widespread use
- •No prior systematic reviews have quantified the real efficacy of EHV-1 vaccination against disease outcomes
- •EHV-1 infection causes variable disease severity including lethal outcomes and triggers movement restrictions particularly during neurological outbreaks