Antibodies aren’t the only immune cells needed to fight off COVID-19—T cells are equally important and can step up to do the job when antibodies are depleted, suggests a new Penn Medicine study of blood cancer patients with COVID-19 published in Nature Medicine. The researchers found that blood cancer patients with COVID-19 who had higher CD8 T cells, many of whom had depleted antibodies from cancer treatments, were more than three times likelier to survive than patients with lower levels of CD8 T cells.