For start in qm you are toast. With no heal she will bleed you to death and no cleanse means she will stack a lot of DOTS with round and round skill 
But in SL its different. The comp that TOTALLY makes her useless is a long forgotten team comp called double healer.
All of her dmg is DOTS and her ulti is strong only when you have low hp. So if you are loaded with heals its almost like she aint there.
Going with 2 heals of which 1 does dmg(like khara,lili or reghar) + 1 pure healer like ana or lucio will make your team way stronger then theirs.
And if you can get ana its even better.You get 2 healers that can keep your team topped gutting quira dots while ana + reghar or khara can help focus and kill targets or boost your comp with bloodlust and nano.
Iām dia 3 and me and my friend won nearly all of matches like these. Quira is useless vs high heal comps since her single dmg sucks while nano,iron fists,bloodlust and uther chain cc can murder someone way before they can go over your massive sustain.
She guts her team burst kill potential.And 2 heal comps LOVE outsustaing vs enemy that cant kill anything.
I dont even have her and yet she is soo ez to counter.Half her darn kit is strong only if you are under 50% hp. So dont be.The other half is high dmg with dots. Then pump equal amount of heals 