Equine Rhino EHV-1 has been around for at least the last thirty years. This Virus should be approached just like any other infectious disease.
Prevention always starts with a solid Nutrition Program to allow the horse to develop a solid immunity against infectious diseases. Reduce stress, as in hauling long distances, temperature extremes, new environments, new feed programs, internal parasite problems and over work.
The number one way to prevent infectious diseases is to maintain a solid vaccination program. Rhino EHV-1, EHV-4 along with the Flu virus vaccinations do not develop immunity that last more than 4 months.
My suggestion has always been to vaccinate horses that will be exposed to other horses with a Rhino Flu vaccine every 4 months. Even though the vaccine companies do not have data on prevention of the nervous Rhino with the vaccines, my experience shows that these horses have less of a chance of developing Nervous Rhino.