I have a 3 month old and I just woke up with sore throat and runny nose !!!

Any advice how to avoid for getting my little one sick , I don’t Brest feed , I have try so hard to avoid this, my 3 step kids they all have been sick since she was born back to back each one and I didn’t let them be around her , than my SO got sick and he is finally doing much better but same I had him away from the baby , NOW IM THE ONE GETTING SICK!!!! Please any advice how to prevent for my LO to get sick , what can i do since I’m the one with her 24/7