This article is from the Getting A Cat FAQ, posted to rec.pets.cats newsgroup. Maintained by Cindy Tittle Moore with numerous contributions by others.
Young kittens need a series of vaccinations ("kitten shots") to help protect them from feline Herpesvirus (Rhinotracheitis), Calicivirus, and Panleukopenia. Many commonly given kitten shots also protect against Chlamydia. For the best immune response, the kitten shots are given at three- or four-week intervals from age 7 or 9 weeks to age 14 or 16 weeks.
If your new cat is a rescued adult or older kitten, it may not have had its shots as a young kitten. In that case, your vet may need to start the vaccination series at the first vet visit.
Rabies shots are a good idea if you plan to let your cat out. Rabies is onthe rise in wild animals, especially raccoons. Rabies shots are also required in many states. The initial rabies shot can be given at age 16 weeks.
Many people also vaccinate their cats against Feline Leukemia. This vaccine is expensive, but it is recommended if your cat goes outdoors.
There is a relatively new vaccine available now for Feline Infectious Peritonitis (FIP). There is some controversy over the safety and effectiveness of this vaccine. Many vets do not recommend its use.