Cats need to be vaccinated once a year.
Kittens need their first vaccination when they are 2-3 months old, followed by a feline triple vaccine every 21 days for a total of 3 shots, and then a rabies vaccine 7 days later. This is because kittens lack maternal antibodies after weaning, making them highly susceptible to viral infections. After kittens reach adulthood, they need annual booster vaccinations. 
The main vaccines cats receive are the feline triple vaccine and the rabies vaccine. If the cat is kept entirely indoors, it is advisable to give it the feline triple vaccine every three years, as cats have less chance of being exposed to viruses indoors. However, the rabies vaccine is mandated by the government to be given annually.
