A lower supply of a certain type of immune cell in older people that is critical to fighting foreign invaders may help explain their vulnerability to severe COVID-19, scientists say. When germs enter the body, the initial “innate” immune response generates inflammation not specifically targeted at the bacteria or virus. Within days, the more precise “adaptive” immune response starts generating antibodies against the invader along with T cells that either assist in antibody production or seek out and attack infected cells.
