Until your child's immune system, gets used to the unique germs there, at THIS environment, she will get sick.
Even in an office, this can happen. Even with adults.
It can take even a year, to get used to.
Anytime, a kid enters a new environment with kids, this will happen.
Now, bear in mind, even if the Daycare is clean and they clean the premises... EVERYDAY a kid arrives at Daycare/school.... with germs.
Kids, will have dirty hands/wipe their noses with their hands/touch and grab things that other kids touch/they will sneeze or cough into their hands not their elbow/they will touch things with their snotty hands etc. SO... it cannot be avoided. Kids... do not have, perfectly controlled, hygiene or impulses, to contain their own germs or dirty hands or faces.
Many kids also touch other kids, to hug or kiss them. Or while playing.
Thus... kids get sick.
Even if the Daycare is clean and they clean/disinfect everyday and they have the kids wash hands.
I have a friend, that worked at a school. For that 1st year of her employment, she got sick EVERY month, for ONE year. Until her immune system, got used to, THAT particular environment and its unique germs.
My son, who rarely gets sick... once he went to Preschool, he was getting sick/colds, every month too. Sometimes every 2 weeks. But he was fine.
Even our Pediatrician's own daughter, had that happen once she started Preschool.
Getting enough sleep/naps... are IMPORTANT for the Immune System. This is how, a body gets strengthened.
So, make sure she naps and gets enough sleep.
This is key.
Getting enough sleep.