Do you have any other symptoms ?
I haven't had any infections, but I definitely have the dry cough. I heard that Sjogrens causes the lungs to dry out for some people. So, that will explain this "smokers" cough, when I don't smoke and never have. I agree that when the organ is dry, you lose the first line of defense. I can't honestly answer your question like a doctor would, but I have to say that once anything is dry, it's open to infections. See if you can get your hands on some fish oil supplements, and maybe those will help your dryest parts. I can't promise anything, but fish oil supplements are good for your body. Also Vitamin E, but too much of that is not good.