There are two strains they have vaccines for, the H3N8 and the H3N2. We have not seen any of the H3N8 in our area, but the H3N2 has been in our area and still peaks it's nasty little head up around the USA. If not recommended by boarding/grooming/dog parks, we highly recommend it! Though, like the human flu shot, it may not protect your pet 100%, it will help lower the severity of illness, and has been known to prevent pneumonia in dogs that have contracted the flu. Plus, if your pet is vaccinated against the influenza and does become infected with the virus, the vaccine manufacturer will pay for testing and treatment.