LOL I love that..... There are multiple combinations of equine vaccines so his 5-way and some company's 5-way may not be the same.
Basic (core) vaccines for horses that should be given yearly are: EEE, WEE, WNV, Tetanus and Rabies. Since your vet said WNV and a 5-way, I would assume he is recommending a EEE, WEE, Tetanus, Influenza and EHV since Rabies is generally sold only to veterinarians and he mentioned WNV seperately.
Depending on your horse's use/situation, you may need to booster the Influenza and EHV (Rhino) anywhere from every 3-4 months to every 6 months. This is because Influenza and EHV vaccines only provide effective resistance to disease for about 3-6 months depending on the brand used and exposure to other horses is the main risk factor for these diseases.
It is always a good idea to have vaccines given by your vet as that keeps you on the "active client list" because he has to have seen your horse within a reasonable length of time in order to legally make any recommendations over the phone. And because vets are more likely to put their active clients ahead of inactive or never seen clients when they get emergency calls.
Licensed Veterinary Technician