Taking a bath generally lowers your BMR or basal metabolic rate, in short decreases your temperature. Basically virus/bacteria will proliferate a lot easier in your body if it is cold since your immune system has been a bit compromised. I mean fever is a defense mechanism of the body to kill those germs, in other words heat kills virus/bacteria or prevent them from spreading further. But too much heat is also dangerous so TSB or tepid sponge bad is advisable.
Unless youre a mess or very unhygienic in which the risk of creating more bacteria/virus is inevitable, taking a bath is optional. But if youre dringking anti biotic, eating, resting well then go on.