Considering it's Cirno, who, as a fairy, should be, if not immune, highly resistant, an *ice* fairy, and thus even less likely to get a cold, and an idiot, with the saying that 'Idiots can't catch colds'....
...since Cirno is the strongest.Even now she would always be full of spirit......but I'll try to believe in her too.Cirno would certainly not lose to illness.
