Although in the past annual vaccination was recommended, this is no longer considered appropriate for every vaccine. In 2006 the American Animal Hospital Association published new canine
vaccination guidelines, which specified that following the initial puppy series and the first adult distemper/parvovirus vaccination, subsequent vaccinations only need to be given every 3 years or longer. There is abundant evidence that the immunity to distemper/parvo is extremely long lasting.
Vaccination for leptospirosis does need to be given every year as this does not produce the same long-lasting immunity.
The frequency of rabies vaccination is dictated by law.
Although generally safe, vaccination is not always benign. Although in general vaccine reactions are mild and easily treatable, serious, sometimes fatal, reactions can occur.