Someone with a cold sore held my baby

A visitor can over and held my six week old baby. It wasn’t until after she had the baby in her arms I noticed the remnants of a cold sore that she covered up pretty well with make up. She didn’t kiss her, but her face was pretty close to the baby. I’m pretty panicked. I said the baby needed to be changed, pretended she had a blow out, and gave her a bath.

Anyone have experience with this? Just wondering how worried I should be.