A: Feline coronavirus (FCOV) is very common and usually doesn't cause any issues aside from mild diarrhea. In less than 10% of infected cats feline coronavirus virus will multiply and mutate, resulting in an infection known as feline infectious peritonitis virus (FIPV) that will multiply and spread throughout the cat’s body. It can cause an extreme inflammatory reaction in the tissues surrounding the abdomen, kidney, or brain. Once a cat develops FIP, the disease is usually progressive and almost always fatal without treatment. Currently the only clinically demonstrated effective treatment is a biochemical compound called GS-441524, which is a intermediary of the popular drug Remdesivir that is used to treat humans with sever symptoms of the Covid-19 infection. Feline coronaviruses cannot be passed from cats to humans.