I have RA and Hashimoto's with additional autoimmunity including SFN. I don't get viruses ever these days but when I was on the higher dose of Methotrexate I found that I did get a succession of bugs - however my joints and nerve pain were much improved so it was a mixed bag. I think my immune system is very overactive now because I have been exposed to all the winter viruses including sick bugs and heavy colds and none has affected me yet. There are some benefits to autoimmunity for some of us it seems but I'd swap the pain and fatigue for the odd bug any day!