Clinical symptoms of calicivirus usually appear 3 to 4 days after infection. Once the cat's immune system starts producing antibodies to the virus, usually about a week after infection, recovery is quick. Unless the cat develops severe pneumonia, the prognosis is excellent. Even after the cat recovers and the symptoms disappear, FCV infection tends to persist, and the cat may be contagious for years.
Veterinarians recommend that all cats be vaccinated against calicivirus when they are vaccinated against FHV-1. Routine vaccination doesn't necessarily prevent infection, but it can prevent the development of severe disease. Kittens should be vaccinated at 8 to 10 weeks of age, then 3 to 4 weeks later. Cats should receive boosters every 1 to 3 years. Keep the cat indoors and away from other cats to prevent spreading the virus. Use a 1:32 dilution of household bleach to clean contaminated areas to prevent re-infecting the sick cat or infecting other cats with the virus.