Feline vaccination is animal vaccination applied to cats. Vaccination plays a vital role in protecting cats from infectious diseases, some of which are potentially fatal. They can be exposed to these diseases from their environment, other pets, or even humans. The practice of recommending and giving vaccines on a fixed schedule with annual boosters has been widely discarded. Current recommendations are based on the philosophy of vaccinating each cat no more frequently than necessary. These recommendations take into account considerations for the efficacy and duration of immunity (DOI) of available vaccines; environmental risks and likelihood of exposure; the specific needs and risks associated with age and overall health status of different cats and cat populations; and socioeconomic limitations. Recommendation vary for: Shelters Owned pets (and based on "inside only", "in and out", or "out only") Breeders Boarding facilities (or animals going into them) Feral cats Community cats TNR (trap–neuter–return) program Specific consideration may be required for: Travel plans Underlying disease conditions of the specific cat Pregnant or lactating/nursing cats Multi-cat households or kitten foster homes Core vaccines are ones that are considered "essential for health" and are recommended for both indoor and outdoor owned domestic cats, as well as community and feral cats. These include: Feline panleukopenia (FPV or FPLV, aka feline parvo or feline distemper) Feline viral rhinotracheitis (FHV, aka herpes virus) Feline calicivirus (FCV) Rabies (where the disease is endemic or required by law) Non-core vaccines are recommended only for cats at risk of specific infection. These include: Feline leukemia virus (FeLV) Feline immunodeficiency virus (FIV) Chlamydia felis Bordetella bronchiseptica National, international, and global vaccination guidelines by professional veterinary advisory boards are regularly updated and available for on-line viewing or download.