Theory suggests thymus plays role in severity of COVID

Eve Glazier, M.D., and Elizabeth Ko
Elizabeth Ko, M.D. and Eve Glazier, M.D.

Dear Doctor: What's the connection between the novel coronavirus and the thymus gland? A friend of ours who is a doctor says it's probably what keeps young kids from getting so sick. I've never even heard of the thymus. What does it have to do with coronavirus?


If you place your finger at the notch at the top of your breast bone and draw a vertical line downward a few inches, you've traced the location of your thymus. It's made up of two roughly triangular lobes, which sit behind the breastbone and between the lungs. The thymus has several functions, but perhaps its most important role is to help produce the cells that will become T-lymphocytes, or T-cells. (The "T" stands for thymus-derived.) These are white blood cells that protect the body from bacteria, fungi, viruses and other pathogens.



Emerging research into COVID-19 has shown a marked decrease in the number of T-cells in some gravely ill patients. Scientists are now asking whether age-related thymus decline, which means T-cells aren't quickly replaced, may play a role in the severity of illness seen in older adults. The flip side of this is whether, due to their robust production of T-cells, children's immune systems are able to stay one step ahead of the novel coronavirus. It's only a working theory, but it shows promise, and research into how this may affect and inform treatment continues.
