I agree with jbaruta...and yet, when my baby acts ill I kind of panic and forget. But, I know the above to be true. If baby does start to get sick, keep an eye on hydration (wet diapers). A temperature is a sign of the body doing a good job of fighting something off so don't be afraid of a temperature ro treat it prematurely. Maybe call your doctor (or whomever your go-to professional is) and ask ahead of time what they would consider a high fever so you know what number to look for. Plenty of skin-to-skin contact and especially nursing will give her an advantage that the rest of the family doesn't have! Sometimes once they are sick, there is nothing to do but nurse them and wait it out. The Baby Book has some good ideas as far as how to treat symptoms to make the baby more comfortable and also gives you a guideline as far as when to worry.
Check your stash of herbs and supplements...a tea with healthy minerals (nettle for instance) would be a good thing for you to take (for your breastmilk). Also maybe a bit higher doses of vitamin C for a week or two until you think the sickness has passed. I'm talking several grams of C. Try to make sure you're getting enough vitamin A and the B's too. This might be a good time to roast a chicken and then use the carcass to make a nice big batch of bone broth. If nobody else gets sick, then great! But if you freeze the broth and have it on hand, it should be a very nutritious addition to your diet and those wonderful minerals will boost your breastmilk in case baby does happen to get sick later.
Bottom line, hand washing and breastmilk are key like jbaruta said. I have a 2yr old who routinely sneezes directly in her baby sisters face and often kisses her. She's now taken to "tickling" her face to which the baby responds by sucking on the toddlers hand/fingers! Ack! I can't seem to wash hands frequently enough to calm my nerves. At some point you just have to let it be. But, it's the pits when your baby is sick so I understand your concern for sure.