EHV Vaccination: Begin Effective Protection
After a horse is vaccinated for EHV 1-4, when is that horse protected from the virus? Does the vaccine take effect immediately, or is there a two week delay before protection takes full effect?
Adams County Colorado
With any vaccine, there is a delay before protection becomes effective. The time delay is related to if the body has seen the vaccine/disease before - if previously exposed, protection will happen in about 10 to 14 days, if not previously exposed, immunity will take longer and a booster is usually needed. With the respiratory viruses, as in people receiving the flu vaccine, protection is not anywhere near 100%. The horse may still get the virus, but if they do get the virus, they are hopefully not as sick, and the duration of illness is not as long. Finally, the vaccine doesn't protect the horse from the neurologic form of the disease.