Good advice for all: Avoid hand contact Contact Dr. Roach at ToYourGoodHealth@med.cornell.edu.

DEAR DR. ROACH » A few years ago, my sister was diagnosed with an IgA deficiency, which is an autoimmune disorder. She was told by her doctor to avoid large crowds and to never shake hands with anyone. My sister is a major event organizer and was unable to simply quit her job, so she developed a strict practice of bumping elbows. What is interesting is that she noticed she wasn’t getting sick anymore and was able to continue working. Can you please explain what an IgA deficiency is, and why shaking hands is such an issue?

— J.S.B.

DEAR READER » IgA deficiency is a primary immune disorder, and the most common primary antibody defect. There are five types of antibodies, also called immunoglobulins(Ig): IgG, IgM, IgA, IgE and IgD. Each has an important role. IgA is found in secretions, so people with IgA deficiencies may be more prone to develop certain types of infections.

The majority of people with IgA deficiency do NOT need to quit their jobs, and are healthy and able to live normal lives. Most are asymptomatic. If a person with IgA deficiency develops symptoms, it can be recurrent sinus or lung infections; a parasite like Giardia that can cause severe diarrhea, or other intestinal infections; and allergies.

Although IgA deficiency is not, by itself, an autoimmune disorder (it’s an immunodeficiency), people with IgA deficiency can paradoxically develop autoimmune disorders. This is thought to be due to other disorders of the immune system that can exist along with the IgA deficiency. Lupus, autoimmune thyroid disease, Type 1 diabetes and rheumatoid arthritis are among the autoimmune diseases that a person with IgA deficiency is at higher risk for.

Hand contact is a MAJOR way of acquiring viruses and bacteria. In your sister’s case, not getting exposed to so many germs clearly had a big impact. I think many people may find that this last year of masks and social distancing has dramatically reduced infectious illnesses, and I really wonder how people (with or without immune diseases) will react next cold and flu season. I suspect many people will want to return to “normal,” but others will choose to continue mask-wearing and avoiding handshaking.