Why those most at risk of COVID-19 are least likely to respond to a vaccine
Aging immune systems spell trouble for any vaccine candidate, but there are ways to overcome this hurdle.
If you want to pinpoint an organ that’s key to fighting COVID-19—and to understanding why the disease is so hard on older people—point your finger at the middle of your chest and run it up along your sternum. Stop just before you reach your neckline. Right there, nestled just behind the bone in between the lungs, is the gland that captivated Edith Boyd’s curiosity in the 1930s: the thymus.
Boyd set out to understand how aging affects its size. She combed through data from 10,000 autopsies collected at the University of Minnesota, where she was an assistant professor, and analyzed information gathered by scientists from four European countries too. She confirmed an interesting pattern: The thymus, about the size of