The one and only time myboy was given this vaccine via nasal spray was as a 6mo old and because I had him in a good day care a couple hours once per week. At the time, we also had our 12 yr old girl at home. This is circumstantial but... after waiting the correct amount of days from the nasal spray, he went back to daycare. Within I think two weeks, one or two dogs from day care contracted the virus and a couple days later so did my old girl. It was the only time she was ever sick and it scared the dickens out of me. I stopped the daycare because of that vaccine requirement. It just wasn't worth risking that again.
"If you can't see his soul when you look in his eyes, then you need a seeing-eye dog"