Test flu can be avoid by starting at a low dose and going up from there each week. But most of us are into getting blood levels up right away through short half life esters or by the method of front loading. For me, no what compund of test it is, if I start high I usually shock my body into a weakened immune system most severely in the first couple of weeks then after raising immune function a little my body will stay at a low level immune function throughout the rest of the cycle. I've found that in order to avoid a weakened immune system entirely, I start at a low dose and gradually work my way up and down; pyramiding just like the oldschoolers.
Most steroid cycles regardless if there's the onset of "test flu" will result in a weakened immune system. It's just not normal to have 1000% of natural hormone levels circulating in the blood.