Elderly people who get COVID-19 have lower levels of important immune cells, which may explain why they are more likely than younger patients to have severe symptoms or die, new research suggests.
For the study, the researchers analyzed blood samples from 30 people with mild COVID-19, ranging in age from the mid-20s to late-90s. Compared with healthy people, all of the COVID-19 patients had lower numbers of T cells — which target virus-infected cells — in their blood.
But COVID-19 patients over 80 years of age had fewer T cells than those who were younger, and so-called “killer” T cells in older patients produced lower amounts of cytotoxic molecules that find and kill infected cells, the investigators found.
This age-related difference in immune response may partially explain why older COVID-19 patients have more severe illness, according to the authors of the study published this month in the journal mBio.