New research, comparing the immune response among age groups, may help explain why elderly patients face a higher risk of severity and death than younger patients in cases of COVID-19.Older patients with the disease have lower frequencies of the immune cells needed to expel the virus from the body, the researchers found. The study was published this week in mBio, an open-access journal of the American Society for Microbiology.
"Elderly people have more severe diseases compared to young people, and we found that the cytotoxic part of immune control is not as efficient to respond to the virus in older people," said virologist Gennadiy Zelinskyy, Ph.D., at the University Hospital Essen, in Germany, who also led the new study.
He and his colleagues analyzed blood samples from 30 people with mild cases of COVID-19 to observe how T cells, which are necessary for recognition and elimination of infected cells, respond during SARS-CoV-2 infection. Patient ages ranged from the mid-20s to the late 90s.
In all patients, the investigators found that acute SARS-CoV-2 infections led to lower numbers of T cells in the blood of the patients, compared to healthy individuals.
This reduction has been one of many unwelcome surprises from COVID-19, said Zelinskyy.