If you ask this question another way. Is cat coronavirus contagious? The answer is yes.
But does having a cat coronavirus necessarily cause cat-to-stomach transmission? The answer is no.
Feline abdominal transmission is caused by mutations in feline coronavirus. The mutated virus is not contagious. Viruses that do not mutate do not cause feline transmission. Feline abdominal attack may be related to decreased immune function in cats, which is more likely to occur during stress. Multi-cat households don't have to worry too much.