The FVRCP combination vaccination protects cats against feline viral rhinotracheitis, calicivirus, and feline panleukopenia. This vaccination is considered a core vaccination, meaning all cats should receive it, regardless of lifestyle. The combination vaccination is initiated in kittens as young as 6 weeks and is administered every 3-4 weeks until over 16 weeks of age. Adult cats who did not receive the vaccination as kittens should be vaccinated twice, thirty days apart. After the initial series, the vaccination is boosted 1 year later and then is given every 3 years. Cats in high-risk environments like shelters may benefit from being vaccinated more frequently. The viruses can be spread through cat-to-cat interactions as well as via contact with contaminated surfaces.