Definitely of course. You're in a weakened state, with your body's priority to put your immune system of high and defend against any viruses and diseases.
When i get sick usually my perfomance get better :v. But if you don't feel great enough to play do not do it. Mania uses strentgh so being weak probally turns it harder
idk ive played while sick and it didnt really affect performace, i did have a headache while i was sick one time and it was painful for me to even try to play so if its like that maybe dont