Is the condition you have one that makes you immunocompromised? If it is, I would be really careful with this.
The chances of you getting anything from kissing are zero, with the exception of hsv1, if you don't already have it. Hsv1 is the herpes virus that causes cold sores, and if you don't already have it, and are immunocompromised, it could be dangerous for you.
If the condition you have doesn't make you immunocompromised, or you already have it, then kissing is fine.
Obviously, the risk for colds, flus and covid are there, but that's true with non-threesomes.