Generally the virus isn't serious, if caught early, but it can cause complications like pneumonia, which increases the risk. Since flu symptoms resemble other respiratory diseases, canine influenza is often mistaken for kennel cough.
The vaccine is intended for dogs at risk of exposure to the virus, such as those who participate in activities with other dogs or those who go to doggy daycare. The risk groups are the same for dogs who are recommended to receive the kennel cough vaccine.
My dogs are at a moderate risk since they regularly go to a training club and attend dog shows. However, I decided to pass on the vaccine for my crew since I don't board them or bring them to doggy day care. If you're considering the vaccine for your pups, consult your vet.